Re: VMWare file system / database corruption

In response to Merlin Moncure <mmoncure(at)gmail(dot)com>:

> On Mon, Sep 21, 2009 at 4:03 PM, Scot Kreienkamp <SKreien(at)la-z-boy(dot)com> wrote:
> > On the contrary, we've been running PG in production for years now under VMWare.  Same with MSSQL.  We've never had any problems.  Less so than an actual physical machine actually since we can move the server to different physical hardware on demand.  Also makes disaster recovery MUCH easier.
> >
> > However, VMWare does have its places.  A high usage database is not one of them, IMHO.  A moderately or less used one, depending on requirements and the hardware backing it, is often a good fit.  And I agree with Scott about the snapshots.  They do tend to cause temporary communication issues with a running virtual machine occasionally, regardless of OS or DB type.  (The benefits outweigh the risks 99% of the time though, with backups being that 1%.)  In my experience the level of interference from snapshotting a virtual machine also depends on the type and speed of your physical disks backing the VMWare host and the size of the virtual machine and any existing snapshot.  I've been told that in VSPhere (VMWare 4.0) this will be significantly improved.
>
> I agree with pretty much everything you've said. I would never put a
> high load system on vmware, but testing, workstation, development,
> legacy etc is all good. I've never had any type of filesystem
> corruption.

There was a bug in the disk driver for VMWare ESXi not long ago that would
neglect to flush the disk buffers on certain hardware on shutdown. This,
naturally, would lead to horrendous filesystem corruption if you rebooted.
This bit us pretty hard (we use ESXi for our testing/development systems).

The good news is that VMWare has since issued a patch that fixes the
problem. The point being that if you're experiencing filesystem corruption
on VMWare, check your version against their updates and see if that's
the cause.

--
Bill Moran
http://www.potentialtech.com
http://people.collaborativefusion.com/~wmoran/