/tmp clean-up script modification, sessions dying with PHP
It seems there there was a little flaw in the script that I wrote a while ago, any PHP sessions on the server will timeout/die after 1 hour if you run that as an hourly cronjob, I have made a small modification to the script.
The only small modification is that now, it deletes all sess_* files that have not been accessed for 5 days therefore are probably just sitting there and never going to be used again, the rest remain deleted because it’s failed uploads/etc that will never be used again.
#!/bin/bash
# Change directory to /tmp
cd /tmp
# Clean up trash left by Gallery2
ls | grep '[0-9].inc*' | xargs rm -fv
# Clean up PHP temp. session files
find /tmp -atime +5 -name 'sess_*' -print | xargs rm -fv
# Clean up dead vBulletin uploads
ls | grep 'vbupload*' | xargs rm -fv
# Clean up failed php uploads
ls | grep 'php*' | xargs rm -fv
# Clean up failed ImageMagick conversions.
ls | grep 'magick*' | xargs rm -fv
Thanks!
Cleaning up /tmp directory on busy cPanel web hosting servers
Usually, the /tmp directory is one of the frequently accessed directories, temp files of MySQL, PHP and other applications are placed and often if processes die, left over. Uploads using PHP are always uploaded to the /tmp directory till they are complete, if you have some dying processes, you will end up with a filled /tmp directory which is hell.
Why? Because MySQL leaves and uses it’s temporary files in /tmp, and if there is no space in there, queries will start failing. Uploads from PHP or Perl are placed in there till the upload process is over, they cannot be further placed there because there is no more space left. So far, we have failing MySQL & inability to upload complete PHP files, system administrator hell.
Easy fix, you might say? Just a simply rm -rf / should take care of it? Nope. Try that, have fun trying to fix the sockets you deleted, specifically applications that depend on the mysql.sock placed in your /tmp directory, things just got worse. In case you actually did delete everything, just restart the services, they should re-appear, if they don’t, they should be somewhere else and you have to create a symbolic link using li, MySQL’s socket is usually located at /var/lib/mysql/mysql.sock.
The best way is to either have a script that cleans it up hourly if you know what usually fills it up or manually run ls -alhS /tmp | head and looking what’s causing the problem and how to avoid it in the future, I have developed a script that I run on multiple servers with no problems at the moment. It takes care of the most trash caused on a cPanel server
#!/bin/bash
# Change directory to /tmp
cd /tmp
# Clean up trash left by Gallery2
ls | grep '[0-9].inc*' | xargs rm -fv
# Clean up PHP temp. session files
ls | grep 'sess_*' | xargs rm -fv
# Clean up dead vBulletin uploads
ls | grep 'vbupload*' | xargs rm -fv
# Clean up failed php uploads
ls | grep 'php*' | xargs rm -fv
# Clean up failed ImageMagick conversions.
ls | grep 'magick*' | xargs rm -fv
That usually is enough, my suggestion is to have that run as a cronjob every hour, but I’m not going in detail on how to do that, because if you don’t know how to setup a cronjob, perhaps you shouldn’t be messing around in /tmp directories and deleting stuff on the first place!
Update: This script is faulty and will cause you a lot of problems with PHP sessions, please read more information and read the new one here
AACRAID based controllers timing out / aborting / SCSI hang
We’ve been lately starting to use more Adaptec RAID controllers rather than 3ware RAID controllers. 3ware has been nothing but trouble for us, dropping hard drives, even RAID5 arrays are running slower than a regular hard drive with no RAID. Our latest issue was a server just simply having a Kernel Panic when using high IO, our experience with 3ware RAID controllers & Linux is terrible.
On this other side, Adaptec has been great. We’ve been using them for a while now and see no problems at all, however there is just a small catch, Linux usually has a SCSI subsystem timeout of less than 30 seconds which results in a small difference between the controller timeout (at 35 seconds) versus the Linux timeout (at 30 seconds). This usually brings a server to a halt for a couple of seconds (and minutes in cases) till the server recovers, errors like this are thrown in the console:
aacraid: Host adapter abort request (0,1,3,0)
aacraid: Host adapter abort request (0,1,1,0)
aacraid: Host adapter abort request (0,1,2,0)
aacraid: Host adapter abort request (0,1,1,0)
aacraid: Host adapter abort request (0,1,2,0)
aacraid: Host adapter reset request. SCSI hang ?
The best method that usually works best is to increase the timeout higher than 45 to ensure that the Linux timeout does not occur before the RAID controller timeout, this is done per device / array.
echo '45' > /sys/block/sda/device/timeout
echo '45' > /sys/block/sdb/device/timeout
echo '45' > /sys/block/sdc/device/timeout
This should be done to every device, 45 is a good number however you can use what you’d like as long as it’s over 35. If you’re experiencing issues with loads going sky-high with no apparent reason, this might very well be the reason, to check if this is a possible cause, you can run the following
dmesg | grep aacraid
If you see errors like the ones that I have up there, then I suggest using that small workaround, if even after using the workaround, you’re still facing these problems, here are the suggestions/checklist that Adaptec suggests:
- Check for any updated firmware for the motherboard, controller, targets and enclosure on the respective manufacturer’s web sites.
- Check per-device queue depth in SYSFS to make sure it is reasonable.
- Engage disk drive manufacturer’s technical support department to check through compatibility or drive class issues.
- Engage enclosure manufacturer’s technical support department to check through compatibility issues.
Anyhow, just like with every Linux issue, your mileage may vary, so if you know of any other fixes or figured out a way how to fix this, feel free to post it as a comment to help others.
