Date: Fri, 27 Oct 2006 10:06:30 -0400 From: "Bucky Jordan" <bjordan@lumeta.com> To: "Jim C. Nasby" <decibel@decibel.org>, "David Magda" <dmagda@ee.ryerson.ca> Cc: Mike Jakubik <mikej@rogers.com>, stable@freebsd.org Subject: RE: Running large DB's on FreeBSD Message-ID: <78ED28FACE63744386D68D8A9D1CF5D4209DF4@MAIL.corp.lumeta.com> In-Reply-To: <20061027044403.GK26892@decibel.org>
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> -----Original Message----- > From: owner-freebsd-stable@freebsd.org [mailto:owner-freebsd- > stable@freebsd.org] On Behalf Of Jim C. Nasby > Sent: Friday, October 27, 2006 12:44 AM > To: David Magda > Cc: Mike Jakubik; stable@freebsd.org > Subject: Re: Running large DB's on FreeBSD >=20 > On Mon, Oct 23, 2006 at 08:15:04PM -0400, David Magda wrote: > > As for Postgres on FreeBSD, FlighAware seems to be using it some some > > decent amount of data: > > > > >. Receiving the data and processing it puts them about 6 minutes > > >behind real time > > >. Generating one map can be done in about 160 milliseconds of CPU time > > >. Capable of generating several million maps a day > > >. About 1 TB of stored data > > >. Approximately 40 million position updates on air craft per day > > > > http://joseph.randomnetworks.com/archives/2006/05/12/flightaware- > > freebsd-and-postgresql/ >=20 > And that's on a dual opteron with 12G of memory and a run of the mill > RAID10 (for the database that is). Yes.. but how many disks (size/type/rpm?) are in that RAID 10? I'm guessing it's an external enclosure...=20 Also, I know 10k rpm vs 15 doesn't make much of a difference for sequential, but random IO seems to be significantly improved. Granted, it's not as dramatic as adding more spindles... I think the other point that may be relevant is the active section of the data that you're accessing, and how good your design is in terms of being able to access that directly. You could have a 1TB database, but only have a portion that is frequently accessed/updated. In that case, you might just need lots of storage, which is fairly inexpensive these days. Also, your money might be better spent on more RAM- if you can fit most of the active data in memory, that will also have a positive impact on performance. As pointed out, 10GB isn't really that much, especially when you can buy relatively inexpensive servers with 8 or 16 GB of ram. Fitting over half your db in memory is quit a luxury. - Bucky
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