Subject: Re: [HACKERS] PostgreSQL, NetBSD and NFS
To: None <>
From: Chuck Yerkes <>
List: current-users
Date: 01/30/2003 16:20:40
Yeah, I have enough fears running Databases on non-raw devices,
let alone over a network - everything I want a databse for
is compromised by having the data files on a network device.
Speed (100base T gets you maybe 10MB/s throughput with nothing
else there), NFS adds overhead, buffering (non device commits),
locking issues and so forth.

I'd be looking a local disk with a periodic backup via dump
to NFS device or similar.

I know that we couldn't MMAP sleepycat DB files via NFS,
even though we loved the products.  A NetApp guy argued it
with me until I finally found the OTHER NetApp guy to
edumucate him on that.

I love NetApps.  But not for databases.

Quoting Greg Copeland (greg@CopelandConsulting.Net):
> That was going to be my question too.
> I thought NFS didn't have some of the requisite file system behaviors
> (locking, flushing, etc. IIRC) for PostgreSQL to function correctly or
> reliably.
> On Thu, 2003-01-30 at 13:02, mlw wrote:
> > Forgive my stupidity, are you running PostgreSQL with the data on an NFS 
> > share?
> > 
> > D'Arcy J.M. Cain wrote:
> > 
> > >I have posted before about this but I am now posting to both NetBSD and 
> > >PostgreSQL since it seems to be some sort of interaction between the two.  I 
> > >have a NetAPP filer on which I am putting a PostgreSQL database.  I run 
> > >PostgreSQL on a NetBSD box.  I used rsync to get the database onto the filer 
> > >with no problem whatsoever but as soon as I try to open the database the NFS 
> > >mount hangs and I can't do any operations on that mounted drive without 
> > >hanging.  Other things continue to run but the minute I do a df or an ls on 
> > >that drive that terminal is lost.
> > >
> > >On the NetBSD side I get a "server not responding" error.  On the filer I see 
> > >no problems at all.  A reboot of the filer doesn't correct anything.
> > >
> > >Since NetBSD works just fine with this until I start PostgreSQL and 
> > >PostgreSQL, from all reports, works well with the NetApp filer, I assume that 
> > >there is something out of the ordinary about PostgreSQL's disk access that is 
> > >triggering some subtle bug in NetBSD.  Does the shared memory stuff use disk 
> > >at all?  Perhaps that's the difference between PostgreSQL and other 
> > >applications.
> > >
> > >The NetApp people are being very helpful and are willing to follow up any 
> > >leads people might have and may even suggest fixes if necessary.  I have 
> > >Bcc'd the engineer on this message and will send anything I get to them.