On Mon, 31 Mar 1997, Steve Gremban wrote:
- Snapshots when used correctly can save alot of time and
wasted effort. If your data is created and deleted and recreated etc. etc. recurrently such as doing edit/compile/run or when running simulations over and over with incremental changes then snapshots are not a good thing. They will take over all available filesystem space (caveat: depends on how often snapshots are done, the size of your filesystem, and the amount of data that is created/deleted/changed).
This has been a sticky problem with our F220. We currently use the default schedule in the sysadmin guide, more or less, and that means once you get close to running out of disk space you have a problem -- deleting files just shuffles them from the filesystem to .snapshot, so there's no net savings in disk space. And the .snapshot space will cheerfully spill over the 20% default. The only option then seems to be manually removing snapshots to free up disk space, or else wait 10 or so days for snapshots to finally be overwritten. (A dicey proposition with a 95+% full filer.)
I'd like to move to a snapshot schedule with more hourly shots, and few if any daily or weekly shots, so things would naturally expire faster. But the guy who does the tape backups here says it's verrryyy slloowww restoring things from exabyte dumps of the filer, so that may not be an option. Getting away from long waits for exabyte restores was one big selling point of the filer.