[CentOS-virt] Remove Centos from AWS marketplace

Sun Mar 9 16:30:22 UTC 2014
Digimer <lists at alteeve.ca>

On 09/03/14 11:43 AM, Stephen Harris wrote:
> On Sun, Mar 09, 2014 at 11:28:07AM -0400, Digimer wrote:
>> Would you mind elaborating on this? If a snapshot is a point-in-time
>> image of a VM (or even normal FS), why would DB backups be at risk
>> (assuming things like fsync are used)?
>> I'm asking in general terms... no idea if this is something AWS specific.
> Database disk snapshots may include "transactions in flight" and the
> on-disk image may not be in a consistent state.  Databases such as Oracle
> try to work around this by ensuring that writes occur in a specific order
> and have a good "recovery" process (each data file has a change number;
> determine the best change number to start from, roll forward from there
> to recover, then roll back any incomplete transactions) but it's considered
> "crash recovery" and shouldn't be part of BAU activity.  Other databases
> may not be so good at recovery (mysql?) and so you run the risk of database
> corruption if you need to restore the snapshot.
> If you rely on disk snapshots then it's recommended you do a proper db dump
> before the snapshot is taken, so that you can recover the database from
> the dump file and not the snapshot.

Thanks for the reply, Stephen. I also replied to Nico, and my comments 
there can be directed to you, as well. :)

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