[gpfsug-discuss] [EXTERNAL] mmbackup vs SOBAR
p.childs at qmul.ac.uk
Thu Mar 9 16:07:43 GMT 2023
I've been told "you really should be using SOBAR" a few times, but never really understood how to do so and the steps involved. I feel sure it should have some kind of white paper, so far I've been thinking to setup some kind of test system, but get a little lost on where to start (and lack of time).
We currently use mmbackup to x2 servers using `--tsm-servers TSMServer1, TSMServer2` to have two independant backups and this works nicely until you lose a tape when restoring that tape is going to be a nightmare. (read rebuild the whole shadow database)
We started with a copy pool until we filled our tape library up, and then swapped to Protect replication until we found this really did not work very well (really slow and missing files), and IBM surgested we use mmbackup with 2 servers and have two independ backups, which is working very well for us now.
I think if I was going to implement SOBAR I'd want to run mmbackup as well as SOBAR will not give you point in time recovery or partial recovery and is really only a disarster solution. I'd also probably want 3 copies on tape, 1 in SOBAR, and 2x via mmbackup via two backups or via a copy pool
I'm currently thinking to play with HSM and SOBAR on a test system, but have not started yet...... Maybe a talk at the next UG would be helpful on backups, I'm not sure if I want to do one, or if we can find an "expert"
From: gpfsug-discuss <gpfsug-discuss-bounces at gpfsug.org> on behalf of Robert Horton <robert.horton at icr.ac.uk>
Sent: Thursday, March 9, 2023 3:44 PM
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Subject: [EXTERNAL] [gpfsug-discuss] mmbackup vs SOBAR
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I’m setting up a filesystem for “archive” data which will be aggressively tiered to tape using the Spectrum Protect (or whatever it’s called today) Space Management. I would like to have two copies on tape for a) reading back the data on demand b) recovering accidentally deleted files etc c) disaster recovery of the whole filesystem if necessary.
My understanding is:
1. Backup and Migration are completely separate things to Spectrum Protect. You can’t “restore” from a migrated file nor do a DMAPI read from a backup.
2. A SOBAR backup would enable the namespace to be restored if the filesystem were lost but needs all files to be (pre-)migrated and needs the filesystem blocksize etc to match.
3. A SOBAR backup isn’t much help for restoring individual (deleted) files. There is a dsmmigundelete utility that restores individual stubs but doesn’t restore directories etc so you really want a separate backup.
My thinking is to do backups to one (non-replicated) tape pool and migrate to another and run mmimgbackup regularly. I’d then have a path to do a full restore if either set of tapes were lost although it seems rather messy and it’s a bit of a pain that SP needs to read everything twice.
So… have I understood that correctly and does anyone have any better / alternative suggestions?
Robert Horton | Scientific Computing Infrastructure Lead
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