[gpfsug-discuss] mmbackup vs SOBAR

[Stephan Graf]

Hi Rob,

we in Jülich have a long history and experience using GPFS & HSM.
We don't use SOBAR (which is for disaster recovery) but mmbackup (single 
file restore).
In principle it is working fine. But there are two problems.

The first one is if the user rename the file/directory. If renamed, the 
file(s) must be backed up again and will trigger a recall(inline tape 
copy). The same happens if ACLs are modified on files.
This is working, but if we are scaling up (1K ore more files are 
effected, we are storing >40PB in these file systems), the inline tape 
copy for backup is not tape optimized and will take a long time.

If you want more details, you can contact me directly.

Stephan

On 3/9/23 16:44, Robert Horton wrote:
> Hi Folks,
> 
> 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?
> 
> Thanks,
> 
> Rob
> 
> *Robert Horton*| Scientific Computing Infrastructure Lead
> 
> The Institute of Cancer Research | 237 Fulham Road, London, SW3 6JB
> 
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-- 
Stephan Graf
Juelich Supercomputing Centre

Phone:  +49-2461-61-6578
Fax:    +49-2461-61-6656
E-mail: st.graf at fz-juelich.de
WWW:    http://www.fz-juelich.de/jsc/
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Forschungszentrum Juelich GmbH
52425 Juelich
Sitz der Gesellschaft: Juelich
Eingetragen im Handelsregister des Amtsgerichts Dueren Nr. HR B 3498
Vorsitzender des Aufsichtsrats: MinDir Volker Rieke
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