[PLUG] [Fwd: Re: Regarding consistency of data on disk]

Cliff Wells cwells at commandprompt.com
Mon Jan 19 12:29:01 UTC 2004


Jeff Schwaber wrote:

>If you have a filesystem that can freeze an instantaneous snapshot of
>the volume the PG database is on, it works to copy from the snapshot.
>Some people do their backups that way, and it seems to work in practice
>as well as in theory.  But without snapshot capability at the filesystem
>level, you gotta shut down the database while you copy the files.
>  
>
The XFS filesystem supports taking snapshots on live filesystems.  IIRC, 
it uses the journal to cache data so even while the snapshot is being 
taken the filesystem isn't locked (up to some limit obviously).

Cliff




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