Posts Tagged ‘kernel’
Tuesday, May 22nd, 2012 
To continue with my lately ASCII centered articles I found hasciicam
hasciicam is a program to stream ASCII video over the network on Linux and probably can be easily made working on FreeBSDtoo.
The project concept is interesting in a matter of fun (play) point of view, however not too usable as we all know ASCII character looking faces doesn't look too pretty.
Below is the Debian (Squeeze) package description:
noah:~# apt-cache show hasciicam|grep -i description -A 7
Description: (h)ascii for the masses: live video as text
Hasciicam makes it possible to have live ASCII video on the web. It
captures video from a tv card and renders it into ascii, formatting the
output into an html page with a refresh tag or in a live ASCII window or
in a simple text file as well, giving the possibility to anybody that has a
bttv card, a Linux box and a cheap modem line to show a live ASCII video
feed that can be browsable without any need for plugin, java etc.
Homepage: http://ascii.dyne.org/
On hasciicam Project webpage is it is stated as a hardware you need to have:
"As hardware you need to have a webcam or a videocard supported by "video 4 linux", most of the gear you can buy around should work well."
To install and test it I run:
noah:~# apt-get --yes install hasciicam
Though it is stated on the project website supposed to work display video fine with most 'linux ready' webcams, it didn't with this very standard one.
Here is the exact WebCamera model as identified to the kernel:
noah:~# dmesg|grep -i camera
[ 1.433661] usb 2-2: Product: USB2.0 Camera
[ 10.107840] uvcvideo: Found UVC 1.00 device USB2.0 Camera (1e4e:0102)
[ 10.110660] input: USB2.0 Camera as /devices/pci0000:00/0000:00:1d.7/usb2/2-2/2-2:1.0/input/input11
By the way, I use the very same CAM daily on for Skype video calls as well as the Camera is working with no problems to save video or pictures inside Cheese
Here is the exact WebCamera model as identified to the kernel:
noah:~# dmesg|grep -i camera
[ 1.433661] usb 2-2: Product: USB2.0 Camera
[ 10.107840] uvcvideo: Found UVC 1.00 device USB2.0 Camera (1e4e:0102)
[ 10.110660] input: USB2.0 Camera as /devices/pci0000:00/0000:00:1d.7/usb2/2-2/2-2:1.0/input/input11
The just installed deb has one binary file only /usr/bin/hasciicam. To test it with the camera I issued:
noah:~# hasciicam -d /dev/video0
HasciiCam 1.0 - (h)ascii 4 the masses! - http://ascii.dyne.org
(c)2000-2006 Denis Roio < jaromil @ dyne.org >
watch out for the (h)ASCII ROOTS
Device detected is /dev/video0
USB2.0 Camera
1 channels detected
max size w[640] h[480] - min size w[48] h[32]
Video capabilities:
VID_TYPE_CAPTURE can capture to memory
!! error in ioctl VIDIOCGMBUF: : Invalid argument
Unfortunately as you see from the output, it failed to detect the web camera model.
The exact camera besides its kernel detection naminf is a cheap external USB 2.0 (fake brand / nonanem) "universal" Web PC Camera (SUPER .3mega pixel)
For those who have a further interest in building and installing hasciicam on other Linux platforms than Debian and Ubuntu or whoever wants to look in the code check check Project webpage is. For those who are less of programmers (like me) the project is written in C programming language and uses aa-lib in order to render the video to ASCII.
On the site you will notice two totally schizophrenic looking pictures of presumably the project head developer …
As I read in man hasciicam manual page it's said to be able to generate ascii plain text and html files as well as directly to write the output to console, which later probably can be streamed via the network.
Pitily as it didn't detect my camera I couldn't make some testing of its network capabilities.
A Streaming of ASCII couuld be done through pushing the .html output to a webserver and setting a php or javascript to loop through and refresh the browser over the uploaded files every sec or so.
Also I assume the ASCII video output saved in plain console could be streamed via netcat or some tiny scripted perl or bash script and directly observed via a telnet or ssh connection.
One playful way I can think of checking a stored video without the use of FTP is to login via ssh and do:
$ ssh someuser@somehost
$ watch -n 1 "cat video-ascii.html"
🙂
Well something disturbing about hasciicam from a (purely Christian point of view) is it was developed by some kind of non profit organization called RastaSoft on the project website, some of its authors has written JAH BLESS.
As I didn't succeeded seeing it working, I'll be interested to hear if someone who red this article and give it a try can report the web camera model used.
Tags: ascii character, Auto, card, description, dmesg, doesn, Draft, dyne, file, formatting, fun, fun play, gnu linux, HasciiCAM, html page, kernel, linux box, modem line, noah, package, package description, page, pci, plugin java, possibility, Product, project webpage, quot, refresh, show, squeeze, ssh, tag, text, tv card, video, video feed, video on the web, videocard
Posted in Entertainment, System Administration, Various | No Comments »
Wednesday, May 16th, 2012
After finding out How PC Speaker is muted on Linux , I've decided to also disable the annoying beeps on BSD. This is in tandem with the minimalistic philosophy I try to apply to every server I manage.
Also on BSD Desktop machines it is quite annoying especially if csh (C Shell) is used, everytime you press TAB you get the beep sound. On BSD beep sound produced on tab completion is louder than in Linux and that makes it even more annoying …
Disabling pc-speaker beeps on BSDs is done via a sysctl kernel variable:
freebsd# sysctl hw.syscons.bell=0
hw.syscons.bell: 0 -> 0
To further permanently disable on system boot add hw.syscons.bell=0 to /etc/sysctl.conf, e.g.:
freebsd# echo 'hw.syscons.bell=0' >> /etc/sysctl.conf
Well that's it no more mind drilling beeps :)
Tags: annoying beeps, Auto, beep, beep sound, bell, boot, BSD, BSDs, c shell, completion, conf, csh, Desktop, desktop machines, Disabling, Draft, drilling, everytime, freebsd, hw, kernel, kernels, Linux, mind, Mute, nbsp, pc speaker, philosophy, server, Sound, sysctl, system, system boot, tab, tab completion, tandem
Posted in FreeBSD, System Administration | No Comments »
Wednesday, January 31st, 2007 Got the 2 mark on Marketing Exam. Again I’m a looser. I dont’ have nor time nor desire to learn again for this exam.I think I’m not suitable for student. Today we was on a coffee with Mitko, Toto and Dido. Nothing special ordinary day.Yesterday we stayed in Mitko and was installing Gentoo Linux to his laptop. Gentoo’s grub was buggy or something,we didn’t succeeded running the kernel with GRUB, so we decided to switch to LILO. We were able to makethe maching bootable using LILO. Then there was an annying error with REAL_ROOT option. After a lot of wanderingediting of /linuxrc we found the mistake it was a mismatch in lilo a mistake we made writing in it we wrote therereal_boot instead of real_root. In the end everything worked okay. And I went home sleeping.I’m not sure where my life is going to again … I’m completely Lost in the Dark.END—–
Tags: buggy, coffee, desire, dido, end, everything, exam, gentoo, Got, grub, home, kernel, laptop, life, Linux, linuxrc, marketing, mismatch, mistake, Mitko, ordinary day, root, sleeping, something, student, therereal, time, toto, yesterday
Posted in Everyday Life | No Comments »
Friday, December 23rd, 2011 I just bought an USB Camera (my notebook doesn't include an embedded camera). The camera is some infamous brand chineese name Eilondo
and on the camera all that is written is SUPER USB2.0 1.3 mega pixel
I bought exactly this camera because I was said by the shop reseller that the camera works without any driver installations on Windows XP and Windows Vista
On my Debian Squeeze GNU / Linux it was detected in dmesg without any troubles, here is how the camera got detected in my kernel log :
debian:~# dmesg |tail -n 10
[25385.734932] usb 2-1: USB disconnect, address 4
[25388.905049] usb 2-1: new high speed USB device using ehci_hcd and address 5
[25389.050753] usb 2-1: New USB device found, idVendor=1e4e, idProduct=0102
[25389.050757] usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[25389.050760] usb 2-1: Product: USB2.0 Camera
[25389.050762] usb 2-1: Manufacturer: Etron Technology, Inc.
[25389.050936] usb 2-1: configuration #1 chosen from 1 choice
[25389.056056] uvcvideo: Found UVC 1.00 device USB2.0 Camera (1e4e:0102)
[25389.058242] uvcvideo: UVC non compliance - GET_DEF(PROBE) not supported. Enabling workaround.
[25389.059113] input: USB2.0 Camera as /devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/input/input26
I was troubled by the message uvcvideo: UVC non compliance – GET_DEF(PROBE) not supported. Enabling workaround. , and hence looked for an application to test if the camera can recored properly.
While checking in packages available in Software Center , I found a plenty of programs under the search keyword Camera
I however decided to test it using just one application Cheese – A tool to take pictures and videos from your webcam which I've seen to be quite popular among Liunx users.
Cheese is part of GNOME Desktop, so that was another reason I decided to give it a try. I was pleasently surprised about how good these tiny but functional proggie is.
To run Cheese in GNOME I nagivated to the menus:
Applications -> Sound & Video -> Cheese Webcam Booth
Just in case if Cheese is not installed, installing it with apt:
debian:~# apt-get install cheese
Cheese has capabilities to take pictures, a consequential photos take up, as well as create Video movies.
The program has support to apply 12 Effects / (Masks) to add some fun to the pictures or video snapshots.
Probably the best thing about Cheese is its simplistic interface, which for me personally is a main criterion to evaluate a program quality ;).
Tags: Camera, center, Cheese, compliance, DEF, dmesg, doesn, ehci, Eilondo, Gnome, gnome desktop, GNU, hcd, high speed, idVendor, INPUT, kernel, Linux, log, non, notebook, pci, Product, proggie, Search, search keyword, SerialNumber, shop, software, software center, speed usb, squeeze, tail, technology inc, tool, usb 2, usb2, video, webcam, windows xp
Posted in Entertainment, FreeBSD, Linux, Linux and FreeBSD Desktop, Linux Audio & Video | No Comments »
Friday, December 9th, 2011 While reading some log files on one of the co-located servers at UK2.net , I’ve noticed dmesg log was filling in with tons of junk messages like:
[4288245.609762] IPv6 addrconf: prefix with wrong length 48
[4288445.984153] IPv6 addrconf: prefix with wrong length 48
[4288646.296110] IPv6 addrconf: prefix with wrong length 48
[4288846.609119] IPv6 addrconf: prefix with wrong length 48
[4289046.922604] IPv6 addrconf: prefix with wrong length 48
[4289247.267273] IPv6 addrconf: prefix with wrong length 48
[4289447.545800] IPv6 addrconf: prefix with wrong length 48
[4289647.857789] IPv6 addrconf: prefix with wrong length 48
[4289848.169308] IPv6 addrconf: prefix with wrong length 48
[4290048.595104] IPv6 addrconf: prefix with wrong length 48
[4290248.808497] IPv6 addrconf: prefix with wrong length 48
[4290449.103503] IPv6 addrconf: prefix with wrong length 48
[4290649.418747] IPv6 addrconf: prefix with wrong length 48
[4290849.742731] IPv6 addrconf: prefix with wrong length 48
After checking the message to make sure it would not suddeny lead to server hang ups I figured out the message is not dangerous but just an annoying warning that some other (routing) host on the same network as mine is advertising something using IPv6, that doesn’t fit with my IPv6 server config.
Actually the server doesn’t use the IPv6 configuration at all, and the assigned configuration is just some kind of auto set IPv6 IP address.
The server, where this message appeared is powered by 64 bit Debian GNU / Linux Squeeze
To resolve the annoying message, 5 of the kernel sysctl settings needs to be modified with cmds:
debian:~# sysctl net.ipv6.conf.all.accept_ra=0
debian:~# sysctl net.ipv6.conf.all.autoconf=0
debian:~# sysctl net.ipv6.conf.lo.autoconf=0
debian:~# sysctl net.ipv6.conf.eth0.autoconf=0
debian:~# sysctl net.ipv6.conf.eth1.autoconf=0
Furthermore to prevent the IPv6 addrconf: prefix with wrong length 48 to re-appear after future server reboots / boots the two sysctl values of course needs to be included in /etc/sysctl.conf e.g.:
debian:~# echo 'net.ipv6.conf.all.accept_ra = 0' >> /etc/sysctl.conf
debian:~# echo 'net.ipv6.conf.all.autoconf = 0' >> /etc/sysctl.conf
echo 'net.ipv6.conf.lo.autoconf = 0' >> /etc/sysctl.conf
echo 'net.ipv6.conf.eth0.autoconf = 0' >> /etc/sysctl.conf
echo 'net.ipv6.conf.eth1.autoconf = 0' >> /etc/sysctl.conf
My server has 2 etherhet interfaces, eth0 and eth1 that’s the reason I had to set up autoconf kernel the two vars net.ipv6.conf.eth0.autoconf and net.ipv6.conf.eth1.autoconf , for more interfaces more kernel vars (eth2, eth3) etc. needs to be set to “0”
I’ve seen posts online of people complaining about a similar errors to IPv6 addrconf: prefix with wrong length 48, like:
IPv6 addrconf: prefix with wrong length 96
IPv6 addrconf: prefix with wrong length 128
The solution to this messages is also done by setting the above described sysctl kernel vars. Setting the vars will suppress the messages which by the way with time could take up A LOT of disk space and fills /var/log/dmesg with this useless message, hence applying the “fix” is a must 😉
Another thing, I’ve noticed while I was researching about the error and the respective fix is that people on other deb based distributions like Ubuntu as well as on Fedora GNU / Linux had also experienced the issue.
Tags: addrconf, annoying message, autoconf, bit, boots, confdebian, config, confMy, course, Disk, dmesg, doesn, eth, GNU, host, ipv6 configuration, junk messages, kernel, Linux, log, lot, prefix, quot, ra, reason, servers, something, squeeze, suddeny, time, Ubuntu, ups
Posted in Linux, System Administration | 1 Comment »
Monday, November 28th, 2011 
Have you looked for a universal physical check up tool to check up any filesystem type existing on your hard drive partitions?
I did! and was more than happy to just recently find out that the small UNIX program dd is capable to check any file system which is red by the Linux or *BSD kernel.
I’ll give an example, I have few partitions on my laptop computer with linux ext3 filesystem and NTFS partition.
My partitions looks like so:
noah:/home/hipo# fdisk -l
Disk /dev/sda: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x2d92834c
Device Boot Start End Blocks Id System
/dev/sda1 1 721 5786624 27 Unknown
Partition 1 does not end on cylinder boundary.
/dev/sda2 * 721 9839 73237024 7 HPFS/NTFS
/dev/sda3 9839 19457 77263200 5 Extended
/dev/sda5 9839 12474 21167968+ 83 Linux
/dev/sda6 12474 16407 31593208+ 83 Linux
/dev/sda7 16407 16650 1950448+ 82 Linux swap / Solaris
/dev/sda8 16650 19457 22551448+ 83 Linux
For all those unfamiliar with dd – dd – convert and copy a file this tiny program is capable of copying data from (if) input file to an output file as in UNIX , the basic philosophy is that everything is a file partitions themselves are also files.
The most common use of dd is to make image copies of a partition with any type of filesystem on it and move it to another system
Looking from a Windows user perspective dd is the command line Norton Ghost equivalent for Linux and BSD systems.
The classic way dd is used to copy let’s say my /dev/sda1 partition to another hard drive /dev/hdc1 is by cmds:
noah:/home/hipo# dd if=/dev/sda1 of=/dev/hdc1 bs=16065b
Even though the basic use of dd is to copy files, its flexibility allows a “trick” through which dd can be used to check any partition readable by the operating system kernel for bad blocks
In order to check any of the partitions listed, let’s say the one listed with filesystem HPFS/NTFS on /dev/sda2 using dd
noah:/home/hipo# dd if=/dev/sda2 of=/dev/null bs=1M
As you can see the of (output file) for dd is set to /dev/null in order to prevent dd to write out any output red by /dev/sda2 partition. bs=1M instructs dd to read from /dev/sda2 by chunks of 1 Megabyte in order to accelerate the speed of checking the whole drive.
Decreasing the bs=1M to less will take more time but will make the bad block checking be more precise.
Anyhow in most cases bs of 1 Megabyte will be a good value.
After some minutes (depending on the partition size), dd if, of operations outputs a statistics informing on how dd operations went.
Hence ff some of the blocks on the partition failed to be red by dd this will be shown in the final stats on its operation completion.
The drive, I’m checking does not have any bad blocks and dd statistics for my checked partition does not show any hard drive bad block problems:
71520+1 records in
71520+1 records out
74994712576 bytes (75 GB) copied, 1964.75 s, 38.2 MB/s
The statistics is quite self explanatory my partition of s size 75 GB was scanned for 1964 seconds roughly 32 minutes 46 seconds. The number of records red and written are 71520+1 e.g. (records in / records out). This means that all the records were properly red and wrote to /dev/null and therefore no BAD blocks on my NTFS partition 😉
Tags: bad blocks, Blocks, boundary, bsd systems, bytesDisk, copying, cylinder boundary, dd, device boot, Disk, drive, drive partitions, end, everything, ext, fdisk, file, filesystem type, freebsd, gnu linux, hipo, image copies, input file, kernel, laptop, laptop computer, lDisk, linux dev, noah, norton ghost, NTFS, optimal, partition, perspective, quot, sda, sector, sector size, Solaris, tiny program, tool, type, unix program, windows user
Posted in Computer Security, FreeBSD, Linux, System Administration, Various | No Comments »
Tuesday, November 1st, 2011 My FreeBSD router has started running out of space, I looked for ways to clean up some space. So I remembered some programs are generating core files while they crash. Some of these files are really huge and ban be from 1Mb to > 1G.
I used find to first list all my produced core files starting from root directory (/) , like so:
find / -name core -exec du -hsc {} ;
....
Having a list of my core files with the respective core file size and after reviewing, I deleted one by one the cores which were there just taking up space.
It’s a wise idea that core dumps file generation on program crash is completely disabled, however I forgot to disable cores, so I had plenty of the cores – (crash files which are handy for debug purposes and fixing the bug that caused the crash).
Further on I used an /etc/rc.conf – dumpdev=NO , variable which instructs the kernel to not generate core files on program crash:
freebsd# echo 'dumpdev=NO' >> /etc/rc.conf
Next, to make dumpdev=NO , take affect I rebooted the server:
freebsd# shutdown -r now
...
There is a way to instruct every server running daemon to know about the newly set dumpdev=NO by restarting each of the services with their init scripts individually, but I was too lazy to do that.
Tags: ban, conf, confNext, core dump, core dumps, core files, cores, crash, DEBUG, dump, dumpdev, exec, file, freebsd, freebsd router, generation, hsc, idea, init, init scripts, kernel, list, name, obsolete program, plenty, program core, program crash, root, root directory, running out of space, shutdown, Space, taking up space, way, wise idea
Posted in FreeBSD, System Administration | No Comments »
Friday, August 12th, 2011 
I’m responsible for some GNU/Linux servers which are shared hosting and therefore contain plenty of user accounts.
Every now and then our company servers gets suspended because of a Phishing websites, Spammers script kiddies and all the kind of abusers one can think of.
To mitigate the impact of the server existing unwanted users activities, I decided to use the Clamav Antivirus – open source virus scanner to look up for potentially dangerous files, stored Viruses, Spammer mailer scripts, kernel exploits etc.
The Hosting servers are running latest CentOS 5.5. Linux and fortunately CentOS is equipped with an RPM pre-packaged latest Clamav release which of the time of writting is ver. (0.97.2).
Installing Clamav on CentOS is a piece of cake and it comes to issuing:
[root@centos:/root]# yum -y install clamav
...
After the install is completed, I’ve used freshclam to update clamav virus definitions
[root@centos:/root]# freshclam
ClamAV update process started at Fri Aug 12 13:19:32 2011
main.cvd is up to date (version: 53, sigs: 846214, f-level: 53, builder: sven)
WARNING: getfile: daily-13357.cdiff not found on remote server (IP: 81.91.100.173)
WARNING: getpatch: Can't download daily-13357.cdiff from db.gb.clamav.net
WARNING: getfile: daily-13357.cdiff not found on remote server (IP: 163.1.3.8)
WARNING: getpatch: Can't download daily-13357.cdiff from db.gb.clamav.net
WARNING: getfile: daily-13357.cdiff not found on remote server (IP: 193.1.193.64)
WARNING: getpatch: Can't download daily-13357.cdiff from db.gb.clamav.net
WARNING: Incremental update failed, trying to download daily.cvd
Downloading daily.cvd [100%]
daily.cvd updated (version: 13431, sigs: 173670, f-level: 60, builder: arnaud)
Downloading bytecode.cvd [100%]
bytecode.cvd updated (version: 144, sigs: 41, f-level: 60, builder: edwin)
Database updated (1019925 signatures) from db.gb.clamav.net (IP: 217.135.32.99)
In my case the shared hosting hosted websites and FTP user files are stored in /home directory thus I further used clamscan in the following way to check report and log into file the scan results for our company hosted user content.
[root@centos:/root]# screen clamscan -r -i --heuristic-scan-precedence=yes --phishing-scan-urls=yes --phishing-cloak=yes --phishing-ssl=yes --scan-archive=no /home/ -l /var/log/clamscan.log
home/user1/mail/new/1313103706.H805502P12513.hosting,S=14295: Heuristics.Phishing.Email.SpoofedDomain FOUND/home/user1/mail/new/1313111001.H714629P29084.hosting,S=14260: Heuristics.Phishing.Email.SpoofedDomain FOUND/home/user1/mail/new/1305115464.H192447P14802.hosting,S=22663: Heuristics.Phishing.Email.SpoofedDomain FOUND/home/user1/mail/new/1311076363.H967421P17372.hosting,S=13114: Heuristics.Phishing.Email.SpoofedDomain FOUND/home/user1/mail/domain.com/infos/cur/859.hosting,S=8283:2,S: Heuristics.Phishing.Email.SSL-Spoof FOUND/home/user1/mail/domain.com/infos/cur/131.hosting,S=6935:2,S: Heuristics.Phishing.Email.SSL-Spoof FOUND
I prefer running the clamscan in a screen session, because it’s handier, if for example my ssh connection dies the screen session will preserve the clamscan cmd execution and I can attach later on to see how scan went.
clamscan of course is slower as it does not use Clamav antivirus daemon clamd , however I prefer running it without running the daemon, as having a permanently running clamd on the servers sometimes creates problems or hangs and it’s not really worthy to have it running since I’m intending to do a clamscan no more than once per month to see some potential users which might need to be suspended.
Also later on, after it finishes all possible problems are logged to /var/log/clamscan.log , so I can read the file report any time.
A good idea might also be to implement the above clamscan to be conducted, once per month via a cron job, though I’m still in doubt if it’s better to run it manually once per month to search for the malicious users content or it’s better to run it via cron schedule.
One possible pitfall with automating the above clamscan /home virus check up, might be the increased load it puts to the system. In some cases the Webserver and SQL server might be under a heavy load at the exactly same time the clamscan cron work is running, this might possible create severe issues for users websites, if it’s not monitored.
Thus I would probably go with running above clamscan manually each month and monitor the server performance.
However for people, who have “iron” system hardware and clamscan file scan is less likely to cause any issues, probably a cronjob would be fine. Here is sample cron job to run clamscan:
10 05 01 * * clamscan -r -i --heuristic-scan-precedence=yes --phishing-scan-urls=yes --phishing-cloak=yes --phishing-ssl=yes --scan-archive=no /home/ -l /var/log/clamscan.log >/dev/null 2>&1
I’m interested to hear if somebody already is using a clamscan to run on cron without issues, once I’m sure that running it on cron would not lead to server down-times, i’ll implement it via cron job.
Anyone having experience with running clamscan directory scan through crond? 🙂
Tags: antivirus, cake, center, CentOS, Clamav, clamav antivirus, company servers, dangerous files, exploits, gnu linux, hosting servers, impact, Installing, kernel, kind, linux servers, m center, mailer, open source, Phishing, piece, piece of cake, plenty, root, rpm, scanner, script kiddies, spammer, Spammers, time, unwanted files, unwanted users, ver, virus, virus scanner, Viruses, writting, yum
Posted in Linux, System Administration, Web and CMS | 2 Comments »
Saturday, July 23rd, 2011 
I’ve been in a situation today, where one Linux server’s hard drive SCSI driver or the physical drive is starting to break off where in dmesg kernel log, I can see a lot of errors like:
[178071.998440] sd 0:0:0:0: [sda] Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK,SUGGEST_OK
[178071.998440] end_request: I/O error, dev sda, sector 89615868
I tried a number of things to remount the hdd which was throwing out errors in read only mode, but almost all commands I typed on the server were either shown as missng or returning an error:
Input/output error
Just ot give you an idea what I mean, here is a paste from the shell:
linux-server:/# vim /etc/fstab
-bash: vim: command not found
linux-server:/# vi /etc/fstab
-bash: vi: command not found
linux-server:/# mcedit /etc/fstab
-bash: /usr/bin/mcedit: Input/output error
linux-server:/# fdisk -l
-bash: /sbin/fdisk: Input/output error
After I’ve tried all kind of things to try to diagnose the server and all seemed failing, I thought next a reboot might help as on server boot the filesystems will get checked with fsck and fsck might be able to fix (at least temporary) the mess.
I went on and tried to restart the system, and guess what? I got:
/sbin/reboot init Input/output error
I hoped that at least /sbin/shutdown or /sbin/init commands might work out and since I couldn’t use the reboot command I tried this two as well just to get once again:
linux-server:/# shutdown -r now
bash: /sbin/shutdown: Input/output error
linux-server:/# init 6
bash: /sbin/init: Input/output error
You see now the situation was not pinky, it seemed there was no way to reboot the system …
Moreover the server is located in remote Data Center and I the tech support there is conducting assigned task with the speed of a turtle.
The server had no remote reboot, web front end or anything and thefore I needed desperately a way to be able to restart the machine.
A bit of research on the issue has led me to other people who experienced the /sbin/reboot init Input/output error error mostly caused by servers with failing hard drives as well as due to HDD control driver bugs in the Linux kernel.
As I was looking for another alternative way to reboot my Linux machine in hope this would help. I came across a blog post Rebooting the Magic Way – http://www.linuxjournal.com/content/rebooting-magic-way
As it was suggested in Cory’s blog a nice alternative way to restart a Linux machine without using reboot, shutdown or init cmds is through a reboot with the Magic SysRQ key combination
The only condition for the Magic SysRQ key to work is to have enabled the SysRQ – CONFIG_MAGIC_SYSRQ in Kernel compile time.
As of today luckily SysRQ Magic key is compiled and enabled by default in almost all modern day Linux distributions in this numbers Debian, Fedora and their derivative distributions.
To use the sysrq kernel capabilities as a mean to restart the server, it’s necessery first to activate the sysrq through sysctl, like so:
linux-server:~# sysctl -w kernel.sysrq=1
kernel.sysrq = 1
I found enabling the kernel.sysrq = 1 permanently in the kernel is also quite a good idea, to achieve that I used:
echo 'kernel.sysrq = 1' >> /etc/sysctl.conf
Next it’s wise to use the sync command to sync any opened files on the server as well stopping as much of the server active running services (MySQL, Apache etc.).
linux-server:~# sync
Now to reboot the Linux server, I used the /proc Linux virtual filesystem by issuing:
linux-server:~# echo b > /proc/sysrq-trigger
Using the echo b > /proc/sysrq-trigger simulates a keyboard key press which does invoke the Magic SysRQ kernel capabilities and hence instructs the kernel to immediately reboot the system.
However one should be careful with using the sysrq-trigger because it’s not a complete substitute for /sbin/reboot or /sbin/shutdown -r commands.
One major difference between the standard way to reboot via /sbin/reboot is that reboot kills all the running processes on the Linux machine and attempts to unmount all filesystems, before it proceeds to sending the kernel reboot instruction.
Using echo b > /proc/sysrq-trigger, however neither tries to umount mounted filesystems nor tries to kill all processes and sync the filesystem, so on a heavy loaded (SQL data critical) server, its use might create enormous problems and lead to severe data loss!
SO BEWARE be sure you know what you’re doing before you proceed using /proc/sysrq-trigger as a way to reboot ;).
Tags: dmesg, drive, drive scsi, driverbyte, emergency, errorJust, fdisk, filesystems, fsck, hard drive, hdd, hostbyte, init, input output, kernel, Linux, log, machine, mcedit, number, pinky, reboot web, remote reboot, remount, request, Result, sda, sector, server boot, server shutdown, Shell, shell linux, target, tech support, turtle, vim, web front
Posted in Linux, System Administration | 5 Comments »
Sunday, July 17th, 2011 It seems Skype has troubles installing on 64 bit Ubuntu via Ubuntu’s Graphical Package Install manager which in Ubuntu 11.04 is called (Ubuntu Software Center)
During my attempt to take advantage of the nice GUI apt frontend, I encontered the error:
Wrong Architecture amd64
And Skype install failed, as you see in below’s picture (which you might be unable to read since it’s stating the error in Bulgarian 😉
The error is quite understandable, since the Skype deb package which tried to install was built for the i386 architecture.
Since the Software Center was not intelligent enough to work around the issue, I finally fixed it myself using the good old apt-get in terminal, like so:
root@ubuntu:~# apt-get install skype
...
apt did not even complain that the package had a different architecture for i386 and installed skype without any errors as well Skype worked immediately even though the arthictural difference.
This is probably because even though it’s a amd64 Ubuntu it has a kernel module loaded to support i386 binaries 😉
Now my sister can enjoy her skype on the shiny Ubuntu 😉
Tags: amd, apt frontend, architecture, arthictural, attempt, binaries, center, deb, deb package, ERROR, frontend, Graphical, graphical package, Install, issue, kernel, manager, Module, package, root, sister, Skype, software, software center, terminal, Ubuntu
Posted in Linux and FreeBSD Desktop, Linux Audio & Video, Skype on Linux | No Comments »
