[gpfsug-discuss] Snapshots for backups

[Jonathan Buzzard]

On Wed, 2018-05-09 at 12:50 +0000, Andrew Beattie wrote:
>  
> From my perspective the difference / benefits of using something like
> Protect and using backup policies over snapshot policies - even if
> its disk based rather than tape based,  is that with a backup you get
> far better control over your Disaster Recovery process. The policy
> integration with Scale and Protect is very comprehensive.  If the
> issue is Tape time for recovery - simply change from tape medium to a
> Disk storage pool as your repository for Protect, you get all the
> benefits of Spectrum Protect and the restore speeds of disk, (you
> might even - subject to type of data start to see some benefits of
> duplication and compression for your backups as you will be able to
> take advantage of Protect's dedupe and compression for the disk based
> storage pool, something that's not available on your tape
> environment.

The way I see it is that snapshots are not backup. They are handy for
quick recovery from file deletion mistakes. They are utterly useless
when your disaster recovery is needed because for example all your NSD
descriptors have been overwritten (not my mistake I hasten to add). AT
that point your snapshots are for jack.

>  
> If your looking for a way to further reduce your disk costs then
> potentially the benefits of Object Storage erasure coding might be
> worth looking at although for a 1 or 2 site scenario the overheads
> are pretty much the same if you use some variant of distributed raid
> or if you use erasure coding.
>  

At scale tape is a lot cheaper than disk. Also sorry your data is going
to take a couple of weeks to recover goes down a lot better than sorry
your data is gone for ever.

Finally it's also hard for a hacker or disgruntled admin to wipe your
tapes in a short period of time. The robot don't go that fast. Your
disks/file systems on the other hand effectively be gone in seconds.

JAB.

-- 
Jonathan A. Buzzard                         Tel: +44141-5483420
HPC System Administrator, ARCHIE-WeSt.
University of Strathclyde, John Anderson Building, Glasgow. G4 0NG