Re: [TUHS] Quotas - did anyone ever use them?

Several list members report having used, or suffered under, filesystem quotas. At the University Utah, in the College of Science, and later, the Department of Mathematics, we have always had an opposing view: Disk quotas are magic meaningless numbers imposed by some bozo ignorant system administrator in order to prevent users from getting their work done. Thus, in my 41 years of systems management at Utah, we have not had a SINGLE SYSTEM with user disk quotas enabled. We have run PDP-11s with RT-11, RSX, and RSTS, PDP-10s with TOPS-20, VAXes with VMS and BSD Unix, an Ardent Titan, a Stardent, a Cray EL/94, and hundreds of Unix workstations from Apple, DEC, Dell, HP, IBM, NeXT, SGI, and Sun with numerous CPU families (Alpha, Arm, MC68K, SPARC, MIPS, NS 88000, PowerPC, x86, x86_64, and maybe others that I forget at the moment). For the last 15+ years, our central fileservers have run ZFS on Solaris 10 (SPARC, then on Intel x86_64), and for the last 17 months, on GNU/Linux CentOS 7. Each ZFS dataset gets its space from a large shared pool of disks, and each dataset has a quota: thus, space CAN fill up in a given dataset, so that some users might experience a disk-full situation. In practice, that rarely happens, because a cron job runs every 20 minutes, looking for datasets that are nearly full, and giving them a few extra GB if needed. Affected users in a average of 10 minutes or so will no longer see disk-full problems. If we see serious imbalance in the sizes of previously similar-sized datasets, we manually move directory trees between datasets to achieve a reasonable balance, and reset the dataset quotas. We make nightly ZFS snapshots (hourly for user home directories), and send the nightlies to an off-campus server in a large datacenter, and we write nightly filesystem backs to a tape robot. The tape technology generations have evolved through 9-track, QIC, 4mm DAT, 8mm DAT, DLT, LTO-4, LTO-6, and perhaps soon, LTO-8. Our main fileserver talks through a live SAN FibreChannel mirror to independent storage arrays in two different buildings. Thus, we always have two live copies of all data, and third far-away live copy that is no more than 24 hours old. Yes, we do see runaway output files from time to time, and an occasional student (among currently more than 17,000 accounts) who uses an unreasonable amount of space. In such cases, we deal with the job, or user, involved, and get space freed up; other users remain largely remain unaware of the temporary space crisis. The result of our no-quotas policy is that few of our users have ever seen a disk-full condition; they just get on with their work, as they, and we, expect them to do. ------------------------------------------------------------------------------- - Nelson H. F. Beebe Tel: +1 801 581 5254 - - University of Utah FAX: +1 801 581 4148 - - Department of Mathematics, 110 LCB Internet e-mail: beebe(a)math.utah.edu - - 155 S 1400 E RM 233 beebe(a)acm.org beebe(a)computer.org - - Salt Lake City, UT 84112-0090, USA URL: http://www.math.utah.edu/~beebe/ - -------------------------------------------------------------------------------