[Users] backups

Martijn Grendelman martijn.grendelman at isaac.nl
Wed Nov 27 16:44:17 UTC 2013

Blaster schreef op 27-11-2013 17:23:
> On 11/27/2013 4:24 AM, Martijn Grendelman wrote:
>> The problem with snapshot-based backups is, that they are usually only 
>> crash-consistent, meaning that they contain the state of a system's 
>> disks as they would be if you pulled the power plug on a server. If 
>> you restore a system from this type of backup, you would see file 
>> system recovery happening at the first boot, and you risk data loss 
>> from -for example- database servers. 
> The work-around for this is to SSH into the guest first, put the 
> database into backup mode(maybe run sync a time or two to flush out as 
> much from RAM as possible), take the snap shot, ssh back in to resume 
> the database, backup the snap, delete the snap.

Yes, for example for MySQL, you could

1. issue a FLUSH TABLES WITH READ LOCK statement
2. create a snapshot
3. issue a UNLOCK TABLES statement

before starting a backup from the snapshot, to get a consistent backup
of the binary table space.


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