Scratch Disk Space
Written by Todd Green   
Wednesday, 23 January 2008 08:40

Every user in the SoC Facility has space available to them in their home directory, and research groups have space allocated for them in /uusoc/res.  However, these areas are restricted by quotas, and sometimes people need more disk space allocated to them (see our Disk Quota FAQ for more information).  Fortunately, there is a quite a lot of disk space out there for users to use that sits outside of /home or /uusoc/res.

There are two resources that users in the SoC Facility can turn to when they're looking for more disk space:

  • Since /home is mounted from our main NetApp Filer, the only space used on the local disk of SoC Facility Unix machines belong to the operating system, and given the large capacity of most disks these days, that leaves a lot of local disk space available for other use.  We have made that space available as /uusoc/scratch/ on all SoC Facility Unix machines. For example, to access the local disk of the machine, just go to /uusoc/scratch/foo on any SoC Facility Unix machine. These directories are generally not world-writable, but if you would like a directory created for you on any particular machine, just drop us a line at  and we'll be happy to get one set up for you.
  • We have repurposed our old Netapp filer for scratch space. This is accessed just like the local disk space mentioned above, through the directories /uusoc/scratch/{users,res}.

There are a few  important things that you should be aware of using this disk space:

  • THIS SPACE IS NOT BACKED UP. While the space available on ithaca-ha exists on a RAID-6 volume which makes it resilient to disk failures, all other local disk exists on single drives which do occasionally fail. In such a case, we do not have backup copies of this data; if the data is lost it is goneAll critical files should be kept on filesystems served off of our man NetApp Filer (/home, /uusoc/res and /uusoc/sys).
  • LOCAL DISK DOES NOT HAVE SNAPSHOTS. The only filesystems with snapshots are those served up by the NetApp Filers, so if you accidentally remove a file it is gone.
  • WE CANNOT GUARANTEE THE RETENTION OF LOCAL DATA OVER REBUILDS OF THE MACHINE. We will try, however, to not disturb any local partition when doing an operating system upgrade or other rebuild of the local machine, but this is not possible in every scenario. In such a case, it is up to you to backup or otherwise safeguard your data.
  • THERE ARE LARGER OR NO QUOTAS ON THIS SPACE. The Netapp has much larger quotas and local scratch is only limited by the disk partitions.  That being said, users should be aware that these resources are meant for every user in the SoC Facility, and therefore should be judicious in their disk usage.
  • SHELL.CS.UTAH.EDU HAS A TMP DIRECTORY. While most scratch directories are not world-writable and require a directory created for users/groups that would like write access, on our interactive servers there is a /uusoc/scratch/tmp directory that is set to mode 777, so anybody can use that for quick, temporary storage.  If you would like a directory for your own personal use, again, just let us know and we'd be happy to set one up for you.

That all said, the amount of disk space available through /uusoc/scratch is very, very large, and a wonderful place for object files, temporary storage, etc. Through judicious use of cron and rsync, you could even keep several copies of certain data on several machines to help guard against data loss in case of disk failure, but that responsibility is left up to the individual user.