Messages in this thread | | | From | (Peter Benie) | Subject | Re: File system snapshopts: how valuable? | Date | Sun, 15 Mar 1998 17:33:24 +0000 |
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anders.qvist@netg.se writes ("Re: File system snapshopts: how valuable?"): > Colin Plumb wrote: > > > I'm designing another file system, and I've stolen a lot of ideas from > > Netowrk Appliances' WAFL (write anywhere file layout)
> Very valuable, yes, but to a rather small audience.
I don't think the audience is all that small. Backup tapes are great for recovering entire filesystems, but they are too slow for recovering one or two files for just one user. If the filesystem could automatically maintain snapshots users' files on-line, then you've saved yourself a lot of time and hastle. Also, users' files are more likely to be in snapshots than on backup tapes because snapshots are usaully made quite often (~hourly) and kept for weeks.
> I presume (not knowing a > lot aboutWAFL and such) that there are rollback/commit-style calls you can > make to "fix" newly written data in ways similar to what relational databases > usually do.
For home directories, you make the snapshots automatically, and then users can access files by looking in ~/.snapshot/ - users don't even need any special tools.
Another nice feature of the NetApp FAServer is the fact that, modulo filesystem bugs, it does not need fscking. A new filesystem design ought to have this feature since fsck would take quite some time to run on a 50Gb disk.
Peter
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