Sunday, March 23, 2014

Linux -- extending /tmp size, an alternative approach-- not preferred

Sometimes, Linux admins use /root filesystem to hosts special directory like /tmp or /boot.. I prefer sepearing them and using dedicated mount points for hosting those directory. There are several reason for doing so. One of them is ease of administration.
Lets look at an incident that I have faced during Oracle EBS 12.2 installion on a Linux box.
The Linux had 2 gb root filesystem. The root filesystem was not seperated . I mean the special directories was not mounted as seperated devices..
The installation was reporting errors such as ;

Stdout: Extracting 0%..............................................Fatal error encountered during self-extraction.[No space left on device]

After analyzing the log files, I saw that temp filesystem was the problem.. Installation requires more temp , but the OS have only 2gb disk space for root filesystem and all of its contents.. Temp was just one of those directories in root filesystem..  So we had a problem.. Resizing root filesystem was one of our options, but it was costly, as it requires recreating partitions and resizing filesystem.. I  had another mount point with 150gb disk size available so I did a soft link operation and saved the day in 2 mins, but it is not preffed operation, it is risky and should be done in production environments... Anyway, I dont like using soft links in critic environments..

What I did was;

mv /tmp /u01/newtemp
ln -s /u01/newtemp /tmp

Then , I checked the tmp  directory size limit by creating a 2 gb file on it ..
cd /tmp
dd if=/dev/zero of=filename bs=1024 count=2M

Actions above saved the day as it was a non-production system. On the other hand; the important lesson in here was ;
"create separated filesystem layout in Linux installations" 
"By doing so you can deal with the specific directories not the whole root partition in case of a disk space problem" 

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