On Mon, Mar 05, 2018 at 09:51:53AM -0800, Steve Atkins wrote:
> I've been running postgresql instances on ESXi VMs for years with no
> issues. I've not benchmarked them, but performance has been good
> enough despite their running on fairly wimpy hardware. Performance
> relative to bare metal is probably going to be dominated by disk IO,
> and depending on how you're hosting VMs that can be anywhere between
> pretty good and terrible - in a large corporation I'd expect it to be
> pretty good. Just don't skimp on RAM - having your hot data in the
> filesystem cache is always good and can make high latency storage
> tolerable.
One thing to be very careful about is the backup strategy of your
PostgreSQL instances. I would recommend primarily using PostgreSQL
in-core tools like pg_basebackup to do the work and make sure that
things are consistent. Users tend to rely a lot on VM snapshots,
particularly quiesced snapshots without memory footprint, but those
could be the cause of data corruption if not using appropriate
pre-freeze and post-thaw scripts in charge of freezing the partitions
while the snapshot is taken (use different partitions for the data
folder, pg_wal and logs as well!), so this would require extra work from
your side. I am talking about VMware technology here, still you can
find a lot of so-told-useful VM-level backup technologies. Be careful
with those as well when it comes to database backups. You can think
that your backups taken are safe, until you see a corruption which has
been hidden for weeks.
--
Michael
