Re: VMWare file system / database corruption

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.

My .02 cents worth as we are a heavy VMWare user.

Thanks,

Scot Kreienkamp
skreien(at)la-z-boy(dot)com

-----Original Message-----
From: pgsql-general-owner(at)postgresql(dot)org [mailto:pgsql-general-owner(at)postgresql(dot)org] On Behalf Of Alex Gadea
Sent: Monday, September 21, 2009 2:11 PM
To: Scott Marlowe
Cc: pgsql-general(at)postgresql(dot)org; Tom Duffey
Subject: Re: [GENERAL] VMWare file system / database corruption

I'd be careful using VMWARE as a database server for anything other than production. I've had problems with SQL Server and mySQL databases and I am sure that Postgres will experience problems as well.

One thing to look at is whether snapshots are set to be taken while the database is active. If they are, ask the system admin to find another way to make backups of the VM. My experience has been that snapshots cause many problems with databases.

Alex

----- Original Message -----
From: "Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com>
To: "Tom Duffey" <tduffey(at)techbydesign(dot)com>
Cc: pgsql-general(at)postgresql(dot)org
Sent: Monday, September 21, 2009 1:40:33 PM GMT -05:00 US/Canada Eastern
Subject: Re: [GENERAL] VMWare file system / database corruption

On Mon, Sep 21, 2009 at 11:09 AM, Tom Duffey <tduffey(at)techbydesign(dot)com> wrote:
> Hi All,
>
> We're having numerous problems with a PostgreSQL 8.3.7 database running on a
> virtual Linux server w/VMWare ESX.  This is not by choice and I have been
> asking the operator of this equipment for details about the disk setup and
> here's what I got:
>
> "We have a SAN that is presenting an NFS share.  VMWare sees that share and
> reads the VMDK file that make up the virtual file system."
>
> Does anyone with a better understanding of PostgreSQL and VMWare know if
> this is an unreliable setup for PostgreSQL?  I see things like "NFS" and
> "VMWare" and start to get worried.

I see VMWare and thing performance issues, I see NFS and thing dear
god help us all. Even if properly setup NFS is a problem waiting to
happen, and it's not reliable storage for a database in my opinion.
That said, lots of folks do it. Ask for the NFS mount options from
the sysadmin.

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