Snapshot performance

[Skylar Thompson]

Kris Kennaway wrote:
> On Fri, Sep 01, 2006 at 11:08:51AM -0700, Paul Lathrop wrote:
>   
>> Hi all,
>>
>> We're working on deploying a new mail server on FreeBSD 6.1-STABLE. One
>> of the major selling points was the ability to take filesystem snapshots
>> in order to make backups from a consistent filesystem on such a
>> high-traffic system. Unfortunately, when I take a snapshot, performance
>> slows to a crawl - to the point where the system stops responding to
>> network requests (ping, SMTP, etc.). Also, the snapshot takes 10-15
>> minutes to complete.
>>
>> Is this a typical situation? Will I need to schedule downtime for
>> backups in spite of this nifty new feature? Am I doing something wrong?
>>     
>
> Time depends on the size of the filesystem - but you are correct that
> snapshots were not designed with performance in mind (rather, to speed
> up booting after an unclean shutdown by removing the need to wait for
> fsck).
>
> Kris
>   
Are there plans to improve performance of snapshots? Using the
freebsd-snapshot port to link FS snapshots to the automounter is pretty
nifty, but it does kill I/O performance while that's in progress as the
OP mentioned.

-- 
-- Skylar Thompson (skylar at cs.earlham.edu)
-- http://www.cs.earlham.edu/~skylar/


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