/scratch in CentOS 7

Just as we did in RHEL6, the unused space of the hard drive of a host will be available for anyone to use at /scratch.  Nothing has changed in this regard.  However, in light of some recent events, we would like to take this opportunity to talk about /scratch and it's purpose.

The first and perhaps most important thing is: /scratch is NOT backed up in any way.  Any data that you put on /scratch is solely your own responsibility.  If you put critically important files on it, and your machine experiences a hard drive failure, your data could be lost and there may be nothing we can do about it.

/scratch is intended to be what the name intends: a scratch pad, a place to put things which you may need, but which could be lost without much harm.  For example, if you have a program that generates a bunch of temporary information in generating an ultimate solution, /scratch is the ideal place.  Typically the /scratch partition has a LOT more space available than the root filesystem.

For temporary files, please do not use /tmp.  /tmp is a directory for temporary files, but not temporary files explicitly generated by users.  Note that /tmp is part of the root filesystem, which contains enough space to hold the operating system and default programs:

user123@box999[modulefiles]$ df -h /tmp
Filesystem                     Size  Used Avail Use% Mounted on
/dev/mapper/vg_box999-lv_root   50G   20G   31G  39% /

user123@box999[modulefiles]$ df -h /scratch
Filesystem                        Size  Used Avail Use% Mounted on
/dev/mapper/vg_box999-lv_scratch  179G   64M  179G   1% /scratch

Although the hard drive capacity of our various models varies, the above is representative of a typical scenario.  There have been case where users have piled up their data into /tmp and filled out the entire root filesystem, which can cause erratic system behavior.

But I have a huge amount of very important data...

If you find that you have a huge amount of data which you can't afford to lose, but which also won't fit into your home directory, apply for a /data directory.  A /data directory is similar to the /home directory in that it is NFS mounted and backed up, except that it is intended to house raw data that you cannot afford to lose.

Apply for a /data directory here: Data Directory Request Form