Re: PostgreSQL over NFS?

On Fri, 9 Feb 2001, tc lewis wrote:

>
> On Fri, 9 Feb 2001, Shaw Terwilliger wrote:
> > I've been using PostgreSQL for a few years now in various projects, and
> > I've been very happy with its features and performance.
> >
> > I have a client who wants to know how PostgreSQL (7) will perform over
> > NFS. The NFS client is Solaris, the server is a big network storage
> > appliance. The network is probably gigabit ethernet.
> >
> > My first reaction is to tell them they're just crazy, and that's not how
> > a database is intended to work, and they should buy some fast, redundant
> > local storage. I thought I'd ask the designers and users here so I could
> > back up my recommendations.
>
> we use mysql over nfs here. it works fine. the nfs server is a netapp.
> it's mounted over a gigabit ethernet crossover cable to the linux machine
> that runs mysqld. it's unlikely that gigabit ethernet would be much of a
> bottleneck on any modern disks, plus netapp's wafl filesystem is basically
> faster than anything out there right now, so the only overhead is the
> tcp/ip (udp) layer, which probably isn't that expensive. running it over
> a 100megabit line would probably slow things down some, but it all depends
> on how hard you're going to be pushing it.
>
> so the issue left is reliability. i've looked over some of the replies
> already that talk about unreliability in general, async issues, and
> locking issues. here's what you do to avoid all of that: use an nfs
> implementation that works. we use linux 2.2.18 with mount and nfs-utils
> packages from http://nfs.sourceforge.net/. we use nfsv3, not v2, and we
> mount the filesystem with the sync option. problem solved.
>
> i haven't tried this with postgresql, but we actually are planning on
> switching to postgresql down the road, so hopefully it'll be ok. heh.
>

oh, and of course, we only mount the data files on _one_ client. we do
_not_ run 2 mysqlds on the same data. that would probably be very bad
with mysql or postgresql.

-tcl.