Posts Tagged ‘amount’

Fix staled NFS on server with dmesg error log nfs: server nfs-server not responding, still trying

Saturday, March 16th, 2019

NFS_Filesystem-fix-staled-NFS-System-dmesg-error-nfs-server-not-responding-still-trying

On a server today I've found to have found a number of NFS mounts mounted through /etc/fstab file definitions that were hanging;
 

nfs-server:~# df -hT


 command kept hanging as well as any attempt to access the mounted NFS directory was not possible.
The server with the hanged Network File System is running SLES (SuSE Enterprise Linux 12 SP3) a short investigation in the kernel logs (dmesg) as well as /var/log/messages reveales following errors:

 

nfs-server:~# dmesg
[3117414.856995] nfs: server nfs-server OK
[3117595.104058] nfs: server nfs-server not responding, still trying
[3117625.032864] nfs: server nfs-server OK
[3117805.280036] nfs: server nfs-server not responding, still trying
[3117835.209110] nfs: server nfs-server OK
[3118015.456045] nfs: server nfs-server not responding, still trying
[3118045.384930] nfs: server nfs-server OK
[3118225.568029] nfs: server nfs-server not responding, still trying
[3118255.560536] nfs: server nfs-server OK
[3118435.808035] nfs: server nfs-server not responding, still trying
[3118465.736463] nfs: server nfs-server OK
[3118645.984057] nfs: server nfs-server not responding, still trying
[3118675.912595] nfs: server nfs-server OK
[3118886.098614] nfs: server nfs-server OK
[3119066.336035] nfs: server nfs-server not responding, still trying
[3119096.274493] nfs: server nfs-server OK
[3119276.512033] nfs: server nfs-server not responding, still trying
[3119306.440455] nfs: server nfs-server OK
[3119486.688029] nfs: server nfs-server not responding, still trying
[3119516.616622] nfs: server nfs-server OK
[3119696.864032] nfs: server nfs-server not responding, still trying
[3119726.792650] nfs: server nfs-server OK
[3119907.040037] nfs: server nfs-server not responding, still trying
[3119936.968691] nfs: server nfs-server OK
[3120117.216053] nfs: server nfs-server not responding, still trying
[3120147.144476] nfs: server nfs-server OK
[3120328.352037] nfs: server nfs-server not responding, still trying
[3120567.496808] nfs: server nfs-server OK
[3121370.592040] nfs: server nfs-server not responding, still trying
[3121400.520779] nfs: server nfs-server OK
[3121400.520866] nfs: server nfs-server OK


It took me a short while to investigate and check the NetApp remote NFS storage filesystem and investigate the Virtual Machine that is running on top of OpenXen Hypervisor system.
The NFS storage permissions of the exported file permissions were checked and they were in a good shape, also a reexport of the NFS mount share was re-exported and on the Linux
mount host the following commands ran to remount the hanged Filesystems:

 

nfs-server:~# umount -f /mnt/nfs_share
nfs-server:~# umount -l /mnt/nfs_share
nfs-server:~# umount -lf /mnt/nfs_share1
nfs-server:~# umount -lf /mnt/nfs_share2
nfs-server:~# mount -t nfs -o remount /mnt/nfs_share


that fixed one of the hanged mount, but as I didn't wanted to manually remount each of the NFS FS-es, I've remounted them all with:

nfs-server:~# mount -a -t nfs


This solved it but, the fix seemed unpermanent as in a time while the issue started reoccuring and I've spend some time
in further investigation on the weird NFS hanging problem has led me to the following blog post where the same problem was described and it was pointed the root cause of it lays
in parameter for MTU which seems to be quite high MTU 9000 and this over the years has prooven to cause problems with NFS especially due to network router (switches) configurations
which seem to have a filters for MTU and are passing only packets with low MTU levels and using rsize / wzise custom mount NFS values in /etc/fstab could lead to this strange NFS hangs.

Below is a list of Maximum Transmission  Unit (MTU) for Media Transport excerpt taken from wikipedia as of time of writting this article.

http://pc-freak.net/images/Maximum-Transmission-Unit-for-Media-Transport-diagram-3.png

In my further research on the issue I've come across this very interesting article which explains a lot on "Large Internet" and Internet Performance

I've used tracepath command which is doing basicly the same as traceroute but could be run without root user and discovers hops (network routers) and shows MTU between path -> destionation.

Below is a sample example

nfs-server:~# tracepath bergon.net
 1?: [LOCALHOST]                      pmtu 1500
 1:  192.168.6.1                                           0.909ms
 1:  192.168.6.1                                           0.966ms
 2:  192.168.222.1                                         0.859ms
 3:  6.192.104.109.bergon.net                              1.138ms reached
     Resume: pmtu 1500 hops 3 back 3

 

Optiomal pmtu for this connection is to be 1500 .traceroute in some cases might return hops with 'no reply' if there is a router UDP  packet filtering implemented on it.

The high MTU value for the Storage network connection interface on eth1 was evident with a simple:

 

 nfs-server:~# /sbin/ifconfig |grep -i eth -A 2
eth0      Link encap:Ethernet  HWaddr 00:16:3E:5C:65:74
          inet addr:100.127.108.56  Bcast:100.127.109.255  Mask:255.255.254.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

eth1      Link encap:Ethernet  HWaddr 00:16:3E:5C:65:76
          inet addr:100.96.80.94  Bcast:100.96.83.255  Mask:255.255.252.0
          UP BROADCAST RUNNING MULTICAST  MTU:9000  Metric:1


The fix was as simple to lower MTU value for eth1 Ethernet interface to 1500 which is the value which most network routers are configured too.

To apply the new MTU to the eth1 interface without restarting the SuSE SLES networking , I first used ifconfig one time with:

 

 nfs-server:~# /sbin/ifconfig eth1 mtu 1500
 nfs-server:~# ip addr show
 …


To make the setting permanent on next  SuSE boot:

I had to set the MTU=1500 value in

 

nfs-server:~#/etc/sysconfig/network/ifcfg-eth1
nfs-server:~#  ip address show eth1
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 8c:89:a5:f2:e8:d8 brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.1/24 brd 192.168.0.255 scope global eth1
       valid_lft forever preferred_lft forever

 


Then to remount the NFS mounted hanged filesystems once again ran:
 

nfs-server:~# mount -a -t nfs


Many network routers keeps the MTU to low as 1500 also because a higher values causes IP packet fragmentation when using NFS over UDP where IP packet fragmentation and packet
reassembly requires significant amount of CPU at both ends of the network connection.
Packet fragmentation also exposes network traffic to greater unreliability, since a complete RPC request must be retransmitted if a UDP packet fragment is dropped for any reason.
Any increase of RPC retransmissions, along with the possibility of increased timeouts, are the single worst impediment to performance for NFS over UDP.
This and many more is very well explained in Optimizing NFS Performance page (which is a must reading) for any sys admin that plans to use NFS frequently.

Even though lowering MTU (Maximum Transmission Union) value does solved my problem at some cases especially in a modern local LANs with Jumbo Frames, allowing and increasing the MTU to 9000 bytes
might be a good idea as this will increase the amount of packet size.and will raise network performance, however as always on distant networks with many router hops keeping MTU value as low as 1492 / 5000 is always a good idea.

 

Baby boomers and Generation X, Y, Z – Generational Marketing and 4 Common personality stereotype traits of people born over the last 60 years

Saturday, August 18th, 2018

baby-bommers-and-x-y-z-generations

Those who are employed in the realm of Social or Internet Marketing definitely have to know the existence of at least 4 different conditional stereotypes, these are Baby Boomers and Generation X, Generation Y and Generation Z (Millenials).

According to Socielogist Karl Mannheim (who is among the founding fathers of classical socielogy) – "All members of a generation share a similar collective experience" or in other words people are categorized in generations depending on when they were born.

As stereotypes they're generalization of people born in different periods of time and sharing same or similar traits.
Because of the age and the conditions they grew up and as they share those general spirit of time and age, they tend to be more or less behaving in a similar ways in how they think save / spend money or share some common approach to life choices and attitude towards life and worldview.

But before proceeding to the 4 main cohert provisional stereotypes, its worthy to mention how these four common trait generations came to existence with a little bit of pre-history.

The pre WW I and WW II world situation and the First and Second World War played a pivotal role in forming the social conditions necessery for the development of the baby boomers.

* The depression Era people

Born in period: 1912 – 1921 who came at full maturity around 1930-1939 right in the beginning of WW I (all of whom are already deceased) as of 2018 as a cause of the war uncertainty and the havoc and the war conditions were very conservative, compulsive savers, tried their best to maintain a low debt. They had the mindset (responsibility) to leave some kind of legacy to their children. They were very patriotic, oriented towards work before pleasure, had a great respect for authority and had a strong sense of moral obligation. For all this character traits of this people undoubtfully a key role played the strong belief in God mostly all people had at the time.

The next in line conditional stereotype of people that came to earth are the:

* The World War II Generation
 

Born in year period: 1922 to 1927 who came to a mature age exactly at the terrible years of Second World War.

People of that time were either fighters for or against the Axis Powers or the Central Powers with the common shared goal to fight against the enemy (of course there are multiple of people who were just trying to survive and not taking a side in this meaningless war).

The current amount of people living are estimated to few million of deathbed elders  worldwide.

As above conditional generations types mentioned are of importance for historical reasons and most of the people belonging to those depression pre WWI and WW II era are dead or just a few millions an overall in un less-consuming age (excluding the medicine consumption which is higher compared to youngsters).

I'll further proceed further with the Baby Boomers, GEN X, Y, Zs who are de-facto the still active members participating to society and economy more or less.

baby-boomers-generation-x-y-z-chart-table-by-year-of-birth

So what are these 4 Stereotypes of Generations that and why are so important for the modern marketers or business manager?

 

1. BABY BOOMERS also called for a short (Boomers)
 

we-are-who-are-baby-boomers

These are people who have been defined by a birth year range (period) from early to mid 1940s  until 1960 and 1964.

 In Europe and North America, boomers are widely identified with privilege, as many grew up in a time of widespread government subsidies in post-war housing and education, and increasing affluence.

As a group, baby boomers were considered the wealthiest, most active, and most physically fit generation up to the era in which they arrived, and were amongst the first to grow up genuinely expecting the world to improve with time. They were also the generation that received peak levels of income; they could therefore reap the benefits of abundant levels of food, apparel, retirement programs, and sometimes even "midlife crisis" products. The increased consumerism for this generation has been regularly criticized as excessive (and that's for a good reason).

One feature of the boomers was that they have tended to think of themselves as a special generation, very different from those that had come before or that has come afterward. In the 1960s, as the relatively large numbers of young people became teenagers and young adults, they, and those around them, created a very specific rhetoric around their cohort, and the changes they were bringing about. This rhetoric had an important impact in the self perceptions of the boomers, as well as their tendency to define the world in terms of generations, which was a relatively new phenomenon. The baby boom has been described variously as a "shockwave" and with a methapors such as as "the pig in the python".

 

2. Generation X / GEN X

generation-x-who-are-they-gen-x-explained-picture

Generation X is considered the people born in the following birth year period 1960 forward in time until 1980s. A specific feature in the 60s-80s period was the shifting societal values, perhaps the spring of this generation was also connected to the increasing role and spread of communism in the world.
Sometimes this generation was referred as the "latchkey generation".
The term generation X itself was popularized largely by Douglas Coupland in his novel 1991 novel Generation X Tales for an Accelerated Culture

A very common trait for Generation X was the reduced adult supervision over kids when compared to previous generations a result of increasing divorce rates and the increased role of one parent children upbringing (in most cases that was the mother) which had to be actively involved as a workforce and lacked physically the time to spend enough time with its children and the increased use of childcare options in one parent families.

They were dubbed the "MTV" (Music Television) generation – that was a hit and most popular music TV in the early 1990s.
The kids representing generation X were described as slackers, cynical and disaffected.

The cultural influences dominating the tastes and feelings of the teen masses of that generation was musical genres such as punk music, heavy metal music, grunge and hip-hop and indie films (independent films)  produced outside of the major film studio system.

According to many researches in midtime those generation are described as active, happy and achieving a work-life balance kind of lifestyle.

People belonging to Generation X are described as people with Enterpreneural tendencies.

Just to name a few of the celebrities and successful people who belong to this generation, that's Google's founder Sergey Brinn & Larry Page (born in 1973), Richard Stallman (founder of Free Software movement) as well movie and film producer celebrities such as Georgi Clooney, Lenny Kravitz, Quantin Tarantino, Kevin Smith, David Fincher etc.

According to United Kingdom survey study of 2500+ workers conducted by Workfront, GEN X are found to be among the hardest working employees in today's workforce. They are also ranked high by fellow workers for having a strong work ethics (about 59.5%), being helpful (55.4%) and very skilled (54.5%) of respondents as well marked as the best troubleshooters / problem solvers (41.6%) claimed so.
According to research conducted by Viacom, gen x they have a high desire for flexibility and fulfillment at work.

3. Generation Y (Millenials) – GEN Y
 

who-are-generation-y-millenials-explained

Following Generation X came on earth Genreation Y the birth period dated for this kids were years are stretchy year period that this generation is described are years 1980s – 1990s to yearly 2000s where birth period range of those ppl ends.
This kids are descendants of the GEN X and second wave Baby Boomers.
In the public this generation is referred as "echo boomers".

The Millenials characteristics are different based on the region of birth, they're famous for the increased familiarity with communication, media and digital technologies.

millenials-focus-on-technology-innovation-and-their-technological-preferences

There upbringing was marked by increase in liberal approach to politics.
The Great recession crisis of the 2000s played a major impact on this generation because it has caused historical high levels of un-employment among youngsters and led to a possible long term economic and social damage to this generation.

millennials-are-heavily-influenced-by-their-peers
Gen Y according are less brand loyal and the speed of the Internet has led the cohort to be similarly flexible and changing in its fashion, style consciousness and where
and how it is communicated with.

As I am born in 1983 me and my generation belongs to Generation Y and even though Bulgaria before 1991 was a Communist regime country, I should agree that I and many of my friends share a very similar behavior and way of thinking to the GEN Y stereotype described, but as I was born in a times of transition and Bulgaria as a Soviet Union Satellite at the time has been lacking behind in fashion and international culture due to the communist regime, me and my generation seem to be sharing a lot of common stereotype characteristics with Generation X such as the punk-rock, metal, hip-hop culture MTV culture and partly because of the GEN X like overall view on life.

Among most famous representative successful people of the Millenials generation are Mark Zuckerberg (Facebook founder), Prince William (the second in line to the British throne), Kim Jong Un (the leader dictator of North Korea) etc.
 

 

4. Generation Z ( GEN Z) / iGeneration / Generation Sensible (Post Millenials)
 

who-are-generation-y-millenials-explained

Following Millenials generation is GEN Z, demographers and researchers typically set as a starting birth date period of those generation 1990s and mid 2000s. As of time of writting there is still no clear consensus regarding ending birth years.

This is the so called Internet Generation because this generation used the internet and Smart Mobile Phone technology since a very young age, they are very confortable with technology (kinda of wired) and addicted to social media such as Facebook / Twitter / Instagram etc. Because of the level of digital communication, many people of this generation are more introvert oriented and often have problems expressing themselves freely in groups. Also they tend to lack the physical communication and more digitally community oriented, even though this depends much also on the specific personality and in some cases it is exactly the opposite.

 

 * Summary
 

As a Marketer, Human Resources hiring personal specialist, a CEO or some kind of project / business manager it is a good idea to be aware of these 4 common stereotypes. However as this are stereotypes (and a theory) as everything theoritized the data is slighly biased and untrue. The marketer practice shows that whoever conducts a marketing and bases his sales on this theoritizing should consider this to be just one aspect of the marketing campaign those who are trying to sell, stuff ideas or ideology to any of those generation should be careful not to count 100% on the common traits found among the above 4 major groups and consider the individuality of person everyone has and just experiment a little bit to see what works and what doesn't.

Also it should be mentioned these diversification of stereotypes are mostly valid for the US citizens and Westerners but doesn't fully fit to ex-communist countries or countries of the Soviet union, those countries have a slightly different personality traits of person born in any of the year periods defined, same is more or less true for the poor parts of Africa and India, Vietnam, China and mostly all of the coomunist countries ex and current. It should be said that countries who belonged to the Soviet Union many of which are current Russian Federation Republics have a personality traits that are often mixture of the 4 stereotypes and even have a lot of the traits that were typical for the WW I and WW II generations, which makes dealing with this people a very weird experience.

Nomatter the standard error that should always considered when basing a marketing research hypothesis on Generational Marketing (using generational segmentation in marketing best potential customer targets), having a general insight and taking in consideration those stereotypes could seriously help in both marketing as well as HR specific fields like Change Management.

generation-x-y-z-characteristics

If you're a marketer, I recommend you take a quick look also on following very educative article Generational Makarketing and how to target each of the GEN X, Y, Z and Baby Boomers and what works best for each of them.

Nomatter what just like all Theories, the theory of Boomers and the Generation segmantation is not completely true, but it gives a good soil for reasoning as well definitely helps for people involved in sociology and business.

Comments and feedback on the article are mostly welcome as the topic is very broad and there is much more to be said …

Hope the article was interesting to you ….

What was your Generation like?

The Treasures of Hermitage, Saint Peterburg Russia and its imitation Hermitage in Amsterdam

Thursday, January 17th, 2013

Sankt-Peterburg-Hermitage

Since some time, I'm very interested in Russia culture as it is so inter-related to our culture in Bulgaria. .It is sad that nowadays Bulgaria is not with Russia, we share much more cultural and heritage roots with Russia than any Western European county or even generally Europe. Thus I believe for every Bulgarian and generally for anyone interested in art, maybe the most remarkable place to visit if you're in Russia is the city of Saint Peterburg. There is found the Russian National State museum. The Hermitage is a museum which historically used to be Winster Palace (Residency) for the Russian Tsar / King. What is unique about this museum is it is one of the oldest and largest museums in the world. The musem was founded in 1764 and since 1852 is in open for public visits. The museum consists of 3 000 000 unique items. Only a small number of those 3 million are exposed for public visitors. The museum contains artifacts from all around the world including very rare things like Mummy sarcophagus. The amount of gold in mostly everywhere is remarkable the ornaments and everything is amazing. For people who value art it is a must see. I still did not have the opportunity to see it with my own eyes. But even seeing it on a video is very  worthy.


 

The Treasures of Hermitage, Saint Petersburg, Russia (State Hermitage Musem of Russia)

As I'm currently in Holland, it was very interesting to find out one of the worthy things to see in Holland is an imitation of st. Peterburg's Hermitage in Amsterdam. There is plenty of beautiful and unique works in it too, as you can check in below video.


 

Hermitage Museum Amsterdam Tour an imitation of Hermitage State Museum of Russia

Enjoy ! 🙂

Negative impact of Cell Phones (GSM) use on individual and society

Monday, June 25th, 2012

Negative impact of Cell Phones GSM on individual and society

We all live in an age, where cell-phone communication has become a standard part of our daily lives. As with everything new adopted in basic human life. GSM tool inclusion in our life had a severe impact on both individuals and in summary to whole society groups and nations.

The benefits out of having an instant “channel” for communication to anyone else in the world are indoubtfully numerous. However as present tosicety is learned to mostly thing in one direction, most people didn’t have a clear understanding on the negative impact of this little communicators on our mind body and soul.

1.; Negative impact of mobile phones on body level

Whenever we talk over the phone especially when picking up incoming calls or initiating out-going ones, the GSM device has to connect to the closest network cell “dial up” and wait for initialization of remote or local connection. The levels of radiation waves during the two mobiles connects up is higher. Therefore if one moves the phone near his ear listening for the status of call the amount of radiation that enters our brains is slightly higher. The extra-radiation whether mobiles are connecting is also few times more whether our phone is ringning, hence it is unhealthy to put the phone near our ear before we press the Answer Call button.

2.;; Negative effect of continuous mobile phones use on human brain

Knowing about the increased radiation on connection initialization thanksfully one can protect himself by simply not putting the mobile headset near ear on call initialization. Though this “problem” can be partially solved, next comes the health brain damage (tumours) which according to some researches are higher among people who do frequentlong phone call conversations. In long phone calls the brain is exposed for a longer time to the flowing waves making the peer to peer call possible. According to some medical researches, a long and frequent phone calls could be a reason not only for brain cancers but also other misfunctions or damages in normal brain cells functioning.

3.;;; The bad impact of Cell Phones on nervous system

Another health issue which the daily phone use and the constant exposure to mobile network cells radio frequency radiation affects generally our nervous system.

Unexpected phone calls early in morning or late at night are a cause for increased bodily stress and even the fear sometimes for an incoming phone call are a cause for many types of neurological disorders diagnosed by psychiatrists.
Even when we sleep at night the mobile phone periodically connects to the nearest mobile cell generating some almost undetectable “waves contamination”. This constant waves air flow caused by the mobile network cells positioned all around cities is not usual thing for our bodies. This also has some influence on our nervous system as the nervous sysm tends to be a bit more alert because of the waves constantly passing the body. The natural reaction of our bodies nerves is to try to balance itself. As nervous system of different people is not equal some people’s nervous system is more prone to having difficulties to balance the disbalance created by the increased number of mobile air waves.
The result of this to many people is in increased sleeplessnes and hardships to get asleep (according to research taken place in American Academy of Sleep Medicine.).

4.;;;; Lost of social and ethical behaviour in people

There is lately observed a huge shift from a face to face communication to peer to peer (p2p) on the phone. The cellphones breeds a culture of socially group detached people (the communication over phone is rarely a conference) but rather consists of communication between two persons (peer to peer). The p2p communication is not only a primary mean of communication of people exposed to heavy phone use. p2p Communication is a primary communication in Skype, Google Talk and mostly all modern available communication medias and softwares.

As more and more people spend nowdays more time on the mobile than in real communication, this makes them introverted and isolated and increases the inability to deal with real human f2f interaction. In other words continuous phone use re-trains us to communicate with others via the mobile. Besides that according to numerous researches about 40 to 50% of visual communication whether a phone call is used is lost (this also makes negotiation or expressing over phone harder and at least twice longer than in real communication).

The influence of the decreased social abilities cause of the phone use has also an impact on ethical behaviour of people too. The increased lost of communication abilities makes even daily real communication vague and lacking accepted social norms and ethical values. Next to that comes the huge problem of over-simplification of communication. As the line communication over the phone loose half of the communication as well as sometimes there are quality of voice over the network interferences. People are doing their best to simplify the communication adopting short command like like phrases and talking in a slang.

5.;;;;; Addiction to mobile phone use

The use of mobile phone often has a short beep sounds, whether you work on the keyboard receive a phone call or look for some mobile functionality staring at the screen. We’re wearing the mobile everywhere with us so often we do check the mobile screen quite un-consciously (by addiction). Checking the mobile screen to see what time is it has become almost an instinct and an automated learned behaviour.

The continous use of mobile phones makes many people mobile addicts. There are huge amount of people I’ve observed who speaks everyday for few hours (whether everytime they feel lonely they call someone in order not to feel lonely). The mobile phone addiction in youngsters is slighly higher than in adults. Probably the most mobile dependent addicts are kids who were given a mobile to use since there very early years.
Anyways there are tons of adults nowdays who cannot even think to be able to live without mobile and even cannot understand: how can anyone think that life could be possible without a cell phone. This kind of thinking is a direct trait showing an addiction and dependency on the phone such people have.

SWITCH OFF your Mobile Phone and TV at night to save energy!!!

Thursday, June 7th, 2012

TURN OFF YOUR MOBILE PHONE AT NIGHT to SAVE ENERGY and MONEY

We’re constantly being said to reduce energy consupmtion, they sell us new bulbs to save energy, new TVs with energy saving. The newer the computer equipment microwaves or whatever home electrical equipment we buy the more it is said to be saving energy.

So far so good it is true we can reduce energy consumption by producing gadgets which consume less. However there are also another approach to the “green problem” which we never are said about.

It is rather simply instead of saving energy on technology base, we can save energy on physical base. One simple thing to do to save energy with no need to spend money on latest advacement gadgets is to simply make it the old school way.

a -= Learn to switch off your lamps and home equipment whenever its not necessery

If you’re about to go to sleep, you can simply switch off the mobile and use a mechanical clock to wake you up on the morning, this way you have 3 benefits.

1; Less energy will be discharged by the mobile in the time you’re not awake, so you don’t need to charge so frequently the battery and therefore you will draw less energy from the Electrical network hence saving energy.

2; You will not be radiated with a bit less radiation produced by the Mobile phone in order to stay connected to the GSM local located cell.

Though the good this does will not be dramatical it for sure will be better for your health than if the mobile is switched on the whole night.

3; You will not be awakened in morning by some crazy person who just decided to call you early in the morning.
Often this morning unexpected and desired phone calls make you jump off the bed rapidly and hence giving a large dose of stress to your organizm.

-=- Of course switching off the mobile has some disadvantages if you can receive a crucial phone calls during all time of day or night you can’t afford to simply switch off the mobile, this is however not true for most people who work in an OFF-ICE.People working in offices can simply wake up at a scheduled time, get a shower do their morning hygiene and jump to a car or bus to the office so the need for having the mobile switched ON at night is not really needed.

Of course thinking in the same direction, it is logical that switching off the computer earlier when not needed, the wireless home router or the TV is another place from where a huge energy savings can be achieved.

If large amount of people re-learn their energy in-efficient habits to be more energy cautios a HUGE amounts of energy can be saved. This of course can have a positive impact on the monthly energy bills and hence can save you money in monthly expenses.

The TV is surely another big energy draining source, many people have the habit to sleep with a Television switched on. Besides this has a negative impact on the conscious since vast amounts of information are being stored and processed by the conscious and unconscious mind, also the lights emitted from the TV screen prevents the persons body to not have a pieceful rest.

Its rather stupid that companies are constantly ranting on how they improve their products to be energy friendly but they don’t invest even a penny to educate the masses that energy saving does not only depend on how good the technology is produced to save energy but also on how much the people are educated how to use the technology with energy saving in mind.Probably there are plenty of other ways a households can change their habits to save energy. I’ll be glad to hear some other suggestions ,,,

Text Monitoring of connection server (traffic RX / TX) business in ASCII graphs with speedometer / Easy Monitor network traffic performance

Friday, May 4th, 2012

While reading some posts online related to MS-Windows TcpViewnetwork traffic analyzing tool. I've came across very nice tool for tracking connection speed for Linux (Speedometer). If I have to compare it, speedometer is somehow similar to nethogs and iftop bandwidth network measuring utilities .

What differentiates speedometer from iftop / nethogs / iptraf is it is more suitable for visualizing a network file or data transfers.
The graphs speedometer draws are way easier to understand, than iftop graphs.

Even complete newbies can understand it with no need for extraordinary knowledge in networking. This makes Speedometer, a top tool to visually see the amount of traffic flowing through server network interface (eth0) … (eth1) etc.

What speedometer shows is similar to the Midnight Commander's (mc) file transfer status bar, except the statistics are not only for a certain file transfer but can show overall statistics over server passing network traffic amount (though according to its manual it can be used to also track individual file transfers).

The simplicity for basic use makes speedometer nice tool to track for network congestion issues on Linux. Therefore it is a  must have outfit for every server admin. Below you see a screenshot of my terminal running speedometer on a remote server.

Speedometer ascii traffic track server network business screenshot in byobu screen like virtual terminal emulator

1. Installing speedometer on Debian / Ubuntu and Debian derivatives

For Debian and Ubuntu server administrators speedometer is already packaged as a deb so its installation is as simple as:

debian:~# apt-get --yes install speedometer
....

2. Installing speedometer from source for other Linux distributions CentOS, Fedora, SuSE etc.

Speedometer is written in python programming language, so in order to install and use on other OS Linux platforms, it is necessery to have installed (preferably) an up2date python programming language interpreter (python ver. 2.6 or higher)..
Besides that it is necessary to have installed the urwid -( console user interface library for Python) available for download via excess.org/urwid/

 

Hence to install speedometer on RedHat based Linux distributions one has to follow these steps:

a) Download & Install python urwid library

[root@centos ~]# cd /usr/local/src
[root@centos src]# wget -q http://excess.org/urwid/urwid-1.0.1.tar.gz
[root@centos src]# tar -zxvvf urwid-1.0.1.tar.gz
....
[root@centos src]# cd urwid-1.0.1
[root@centos urwid-1.0.1]# python setup.py install
running install
running build
running build_py
creating build
creating build/lib.linux-i686-2.4
creating build/lib.linux-i686-2.4/urwid
copying urwid/tests.py -> build/lib.linux-i686-2.4/urwid
copying urwid/command_map.py -> build/lib.linux-i686-2.4/urwid
copying urwid/graphics.py -> build/lib.linux-i686-2.4/urwid
copying urwid/vterm_test.py -> build/lib.linux-i686-2.4/urwid
copying urwid/curses_display.py -> build/lib.linux-i686-2.4/urwid
copying urwid/display_common.py -> build/lib.linux-i686-2.4/urwid
....

b) Download and install python-setuptools

python-setuptools is one other requirement of speedometer, happily on CentOS and Fedora the rpm package is already there and installable with yum:

[root@centos ~]# yum -y install python-setuptools
....

c) Download and install Speedometer

[root@centos urwid-1.0.1]# cd /usr/local/src/
[root@centos src]# wget -q http://excess.org/speedometer/speedometer-2.8.tar.gz
[root@centos src]# tar -zxvvf speedometer-2.8.tar.gz
.....
[root@centos src]# cd speedometer-2.8
[root@centos speedometer-2.8]# python setup.py install
Traceback (most recent call last):
File "setup.py", line 26, in ?
import speedometer
File "/usr/local/src/speedometer-2.8/speedometer.py", line 112
n = n * granularity + (granularity if r else 0)
^

While running the CentOS 5.6 installation of speedometer-2.8, I hit the
"n = n * granularity + (granularity if r else 0)
error.

After consultation with some people in #python (irc.freenode.net), I've figured out this error is caused due the outdated version of python interpreter installed by default on CentOS Linux 5.6. On CentOS 5.6 the python version is:

[root@centos ~]# python -V
Python 2.4.3

As I priorly said speedometer 2.8's minimum requirement for a python to be at v. 2.6. Happily there is quick way to update python 2.4 to python 2.6 on CentOS 5.6, as there is an RPM repository maintained by Chris Lea which contains RPM binary of python 2.6.

To update python 2.4 to python 2.6:

[root@centos speedometer-2.8]# rpm -Uvh http://yum.chrislea.com/centos/5/i386/chl-release-5-3.noarch.rpm[root@centos speedometer-2.8]# rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-CHL[root@centos speedometer-2.8]# yum install python26

Now the newly installed python 2.6 is executable under the binary name python26, hence to install speedometer:

[root@centos speedometer-2.8]# python26 setup.py install
[root@centos speedometer-2.8]# chown root:root /usr/local/bin/speedometer
[root@centos speedometer-2.8]# chmod +x /usr/local/bin/speedometer

[root@centos speedometer-2.8]# python26 speedometer -i 1 -tx eth0

The -i will instruct speedometer to refresh the screen graphs once a second.

3. Using speedometer to keep an eye on send / received traffic network congestion

To observe, the amount of only sent traffic via a network interface eth0 with speedometer use:

debian:~# speedometer -tx eth0

To only keep an eye on received traffic through eth0 use:

debian:~# speedometer -rx eth0

To watch over both TX and RX (Transmitted and Received) network traffic:

debian:~# speedometer -tx eth0 -rx eth0

If you want to watch in separate windows TX and RX traffic while  running speedometer you can run in separate xterm windows speedometer -tx eth0 and speedometer -rx eth0, like in below screenshot:

Monitor Received and Transmitted server Network traffic in two separate xterm windows with speedometer ascii graphs

4. Using speedometer to test network maximum possible transfer speed between server (host A) and server (host B)

The speedometer manual suggests few examples one of which is:

How fast is this LAN?

host-a$ cat /dev/zero | nc -l -p 12345
host-b$ nc host-a 12345 > /dev/null
host-b$ speedometer -rx eth0

When I red this example in speedometer's manual, it wasn't completely clear to me what the author really meant, but a bit after when I thought over the example I got his point.

The idea behind this example is that a constant stream of zeros taken from /dev/zero will be streamed over via a pipe (|) to nc which will bind a port number 12345, anyone connecting from another host machine, lets say a server with host host-b to port 12345 on machine host-a will start receiving the /dev/zero streamed content.

Then to finally measure the streamed traffic between host-a and host-b machines a speedometer is started to visualize the received traffic on network interface eth0, thus measuring the amount of traffic flowing from host-a to host-b

I give a try to the exmpls, using for 2 test nodes my home Desktop PC, Linux running  arcane version of Ubuntu and my Debian Linux notebook.

First on the Ubuntu PC I issued
 

hipo@hip0-desktop:~$ cat /dev/zero | nc -l -p 12345
 

Note that I have previously had installed the netcat, as nc is not installed by default on Ubuntu and Debian. If you, don't have nc installed yet, install it with:

apt-get –yes install netcat

"cat /dev/zero | nc -l -p 12345" will not produce any output, but will display just a blank line.

Then on my notebook I ran the second command example, given in the speedometer manual:
 

hipo@noah:~$ nc 192.168.0.2 12345 > /dev/null

Here the 192.168.0.2 is actually the local network IP address of my Desktop PC. My Desktop PC is connected via a normal 100Mbit switch to my routing machine and receives its internet via  NAT. The second test machine (my laptop), gets its internet through a WI-FI connection received by a Wireless Router connected via a UTP cable to the same switch to which my Desktop PC is connected.

Finally to test / get my network maximum thoroughput I had to use:

hipo@noah:~$ speedometer -rx wlan0

Here, I  monitor my wlan0 interface, as this is my (laptop) wireless card interface over which I have connectivity to my local network and via which through the the WI-FI router I get connected to the internet.

Below is a snapshot captured showing approximately what is the max network thoroughput from:

Desktop PC -> to my Thinkpad R61 laptop

Using Speedometer to test network thorougput between two network server hosts screenshot Debian Squeeze Linux

As you can see in the shot approximately the maximum network thoroughput is in between:
2.55MB/s min and 2.59MB/S max, the speed is quite low for a 100 MBit local network, but this is normal as most laptop wireless adapters hardly transfer traffic in more than 10 to 20 MBits per sec.

If the same nework thoroughput test is conducted between two machines both connected to a same 100 M/bit switch, the traffic should be at least a 8 MB/sec.

There is something, else to take in consideration that probably makes the provided example network thoroughput measuring a bit inaccurate. The fact that the /dev/zero content is stremed over is slowing down the zeroes sent over network because of the  pipe ( | ) use slows down the stream.

5. Using speedometer to visualize maximum writting speed to a local hard drive on Linux

In the speedometer manual, I've noticed another interesting application of this nifty tool.

speedometer can be used to track and visualize the maximum writing speed a hard disk drive or hard drive partition can support on Linux OS:

A copy paster from the manual text is as follows:

How fast can I write data to my filesystem? (with at least 1GB free)
dd bs=1000000 count=1000 if=/dev/zero of=bigfile &
speedometer bigfile

However, when I tried copy/pasting the example in terminal, to test the maximum writing speed to an external USB hard drive, only dd command was started and speedometer failed to initialize and display graphs of the file creation speed.

I've found a little "hack" that makes the man example work by adding a 3 secs sleep like so:

debian:/media/Expansion Drive# dd bs=1000000 count=1000 if=/dev/zero of=bigfile & sleep 3; speedometer bigfile

Here is a screenshot of the bigfile created by dd and tracked "in real time" by speedometer:

How fast is writting data to local USB expandable hard disk Debian Linux speedometer screenshot

Actually the returned results from this external USB drive are, quite high, the possible reason for that is it is connected to my laptop over an USB protocol verion 3.

6. Using Speedometer to keep an eye on file download in progress

This application of speedometer is mostly useless especially on Linux where it is used as a Desktop.

However in some occasions if files are transferred over ssh or in non interactive FTP / Samba file transfers between Linux servers it can come handy.

To visualize the download and writing speed of lets say FTP transferred .AVI movie (during the actual file transfer) on the download host issue:

# speedometer Download-Folder/What-goes-around-comes-around.avi

7. Estimating approximate time for file transfer

There is another section in the speedometer manual pointing of the program use to calculate the time remaining for a file transfer.

The (man speedometer) provided example text is:

How long it will take for my 38MB transfer to finish?
speedometer favorite_episode.rm $((38*1024*1024))

At first glimpse it hard to understand (like the other manual example). A bit of reasoning and I comprehend what the man author meant by the obscure calculation:

$((38*1024*1024))

This is a formula used in which 38 has to be substituted with the exact file size amount of the transferred file. The author manual used a 38MB file so this is why he put $((38* … in the formula.

I give it a try – (just for the sake to see how it works) with a file with a size of 2500MB, in below two screenshot pictures I show my preparation to copy the file and the actual copying / "real time" transfer tracking with speedometer's status percentage completion bar.

xterm terminal copy file and estimate file copying operation speed on linux with speedometer preparation

Two xterm terminals one is copying a file the other one uses speedometer to estimate the time remaining to complete the file transfer from expansion USB hard drive to my laptop harddrive

 

Where does Debian GNU / Linux Apache + PHP stores session files?

Tuesday, November 22nd, 2011

In order to debug some PHP session problems on Debian, I needed to check the count of existing session files.
When PHP is compiled from source usually, by default sessions are stored in /tmp directory, however this is not the case on Debian.

Debian’s PHP session directory is different, there the sessions are stored in the directory:

/var/lib/php5

I’ve discovered the session directory location by reading Debian’s cron shell script, which delete session files on every 30 minutes.

Here is the file content:

debian~# cat /etc/cron.d/php5
# /etc/cron.d/php5: crontab fragment for php5
# This purges session files older than X, where X is defined in seconds
# as the largest value of session.gc_maxlifetime from all your php.ini
# files, or 24 minutes if not defined. See /usr/lib/php5/maxlifetime

# Look for and purge old sessions every 30 minutes
09,39 * * * * root [ -x /usr/lib/php5/maxlifetime ] &&
[ -d /var/lib/php5 ] && find /var/lib/php5/ -type f -cmin +$(/usr/lib/php5/maxlifetime) -delete

To check the amount of existing PHP opened session files:

debian:~# ls -1 /var/lib/php5|wc -l
14049

How to find out all programs bandwidth use with (nethogs) top like utility on Linux

Friday, September 30th, 2011

Just run across across a super nice top like, program for system administrators, its called nethogs and is definitely entering my “l337” admin outfit next to tools like iftop, nettop, ettercap, darkstat htop, iotop etc.

nethogs is ultra easy to use, to get immediately in console statistics about running processes UPLOAD and DOWNLOAD bandwidth consumption just run it:

linux:~# nethogs

Nethogs screenshot on Linux Server with Nginx
Nethogs running on Debian GNU/Linux serving static web content with Nginx

If you need to check what program is using what amount of network bandwidth, you will definitely love this tool. Having information of bandwidth consumption is also viewable partially with iftop, however iftop is unable to track the bandwidth consumption to each process using the network thus it seems nethogs is unique at what it does.

Nethogs supports IPv4 and IPv6 as well as supports network traffic over ppp. The tool is available via package repositories for Debian GNU/Lenny 5 and Debian Squeeze 6.

To install Nethogs on CentOS and Fedora distributions, you will have to install it from source. On CentOS 5.7, latest nethogs which as of time of writting this article is 0.8.0 compiles and installs fine with make && make install commands.

In the manner of thoughts of network bandwidth monitoring, another very handy tool to add extra understanding on what kind of traffic is crossing over a Linux server is jnettop
jnettop shows which hosts/ports is taking up the most network traffic.
It is available for install via apt in Debian 5/6).

Here is a screenshot on jnettop in action:

Jnettop check network traffic in console

To install jnettop on latest Fedoras / CentOS / Slackware Linux it has to be download and compiled from source via jnettop’s official wiki page
I’ve tested jnettop install from source on CentOS release 5.7 and it seems to compile just fine using the usual compile commands:

[root@prizebg jnettop-0.13.0]# ./configure
...
[root@prizebg jnettop-0.13.0]# make
...
[root@prizebg jnettop-0.13.0]# make install

If you need to have an idea on the network traffic passing by your Linux server distringuished by tcp/udp/icmp network protocols and services like ssh / ftp / apache, then you will definitely want to take a look at nettop (if of course not familiar with it yet).
Nettop is not provided as a deb package in Debian and Ubuntu, where it is included as rpm for CentOS and presumably Fedora?
Here is a screenshot on nettop network utility in action:

Nettop server traffic division by protocol screenshot
FreeBSD users should be happy to find out that jnettop and nettop are part of the ports tree and the two can be installed straight, however nethogs would not work on FreeBSD, I searched for a utility capable of what Nethogs can, but couldn’t find such.
It seems the only way on FreeBSD to track bandwidth back and from originating process is using a combination of iftop and sockstat utilities. Probably there are other tools which people use to track network traffic to the processes running on a hos and do general network monitoringt, if anyone knows some good tools, please share with me.