Re: backups

Bill Montgomery wrote:

> Bruno Wolff III wrote:
>
>> On Wed, Jun 30, 2004 at 18:23:08 -0500,
>> wespvp(at)syntegra(dot)com wrote:
>>
>>
>>> What do other sites with mondo databases do?
>>>
>>
>>
>> There have been comments from people using storage systems that they
>> can freeze the storage system and get a consistant snap shot of the
>> file system. This can be used to do a restore. It will look just like
>> postgres crashed when coming back up.
>> If you find one of the posts about this in the archives the poster may
>> have more details on their storage systems.
>>
>>
> We achieve the same effect with LVM. An rsync on the live set of files
> is done to get the majority of files that have changed since the last
> snapshot, then an LVM snapshot is taken and the relatively small set
> of files that have changed are rsyncd. This minimizes the lifetime of
> the snapshot. LVM snapshots degrade write performance on the LVM
> volume group on which they reside, due to the dual-write they require,
> so we want them around for as short a time as possible.
>
> Of course, we also tar up the files after the snapshot rsync, in case
> the primary server craps out in the middle of the next hour's
> snapshot/rsync. Otherwise, we might find ourselves resorting to last
> night's pg_dump.
>
> Regards,
>
> Bill Montgomery
>
What's LVM?