From owner-freebsd-questions Thu May 9 3:56:51 2002 Delivered-To: freebsd-questions@freebsd.org Received: from dire.bris.ac.uk (dire.bris.ac.uk [137.222.10.60]) by hub.freebsd.org (Postfix) with ESMTP id 07B4E37B409 for ; Thu, 9 May 2002 03:56:48 -0700 (PDT) Received: from mail.ilrt.bris.ac.uk by dire.bris.ac.uk with SMTP-PRIV with ESMTP; Thu, 9 May 2002 11:56:35 +0100 Received: from cmjg (helo=localhost) by mail.ilrt.bris.ac.uk with local-esmtp (Exim 3.16 #1) id 175lXn-0007LE-00; Thu, 09 May 2002 11:53:07 +0100 Date: Thu, 9 May 2002 11:53:06 +0100 (BST) From: Jan Grant X-X-Sender: cmjg@mail.ilrt.bris.ac.uk To: AMI Cc: FreeBSD-questions Subject: Re: mount_mfs -F option In-Reply-To: <01ff01c1f730$cc2d5b60$0100a8c0@p7> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Thu, 9 May 2002, AMI wrote: > Hello! > > It's very risky way! For any times of cron's script may has your computer > may be restarting... Does you on built-in caching of bsd's file system and > true onward! > > Regards, > Andrew > > > Greetings, > > > > I'm in the process of setting up a new server for testing purposes > mainly, and thought, with 2GB of DDR RAM in it, that mounting the PostgreSQL > database into memory would speed things up a little. Now I'm well aware that > once the machine restarts or shuts off all data in memory is lost; my > question is: will using mount_mfs with the -F option allow changes to the > database to be written back to that file [the asynch option?]. > > Sans using a cron job or some shell script hack, can I mount a database > to memory and have updates written to file while when accessed, its read > from memory? mount_mfs isn't a good idea to do this; I'd try it if you really want to, but you ought to run some benchmarks that simulate the work you'll be doing - you may find it'll be slower than running PostgreSQL "normally". Postgres knows what it's doing and will try to use as much memory as you let it. Look at getting your data across as many disk spindles as you can. There's quite a bit of tuning information on the postgres web site, too (in particular, have a nose around techdocs.postgresql.org) -- jan grant, ILRT, University of Bristol. http://www.ilrt.bris.ac.uk/ Tel +44(0)117 9287088 Fax +44 (0)117 9287112 RFC822 jan.grant@bris.ac.uk Goth isn't dead, it's just lying very still and sucking its cheeks in. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message