Date: Wed, 4 Aug 2004 09:49:54 -0700 From: Brooks Davis <brooks@one-eyed-alien.net> To: Kathy Quinlan <kat-free@kaqelectronics.dyndns.org> Cc: freebsd-hardware@freebsd.org Subject: Re: Big Problem Message-ID: <20040804164954.GB10063@Odin.AC.HMC.Edu> In-Reply-To: <4110C9C7.6080506@kaqelectronics.dyndns.org> References: <4110C9C7.6080506@kaqelectronics.dyndns.org>
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--JP+T4n/bALQSJXh8 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Aug 04, 2004 at 07:34:31PM +0800, Kathy Quinlan wrote: > Hi Guys and Gals, >=20 > First off I am not a troll, this is a serious email. I can not go into=20 > to many fine points as I am bound by an NDA. >=20 > The problem: >=20 > I need to hold a text file in ram, the text file in the forseable future= =20 > could be up to 10TB in size. >=20 > My Options: >=20 > Design a computer (probably multiple AMD 64's) to handle 10TB of memory= =20 > (+ a few extra Gb of ram for system overhead) and hold the file in one=20 > physical computer system. >=20 > Build a server farm and have each server hold a portion eg 4GB each=20 > Server (250 servers (plus a few extra for system overhead) That only gets you to 1TB... > The reason the file needs to be in ram is that I need speed of search=20 > for paterns in the data (less than 1 second to pull out relevent chunks) > > I am sure I have missed some options, right now I am just kicking ideas= =20 > around, the software will be based on FreeBSD with some major=20 > modifications to address the large amount of ram (probably set it up as= =20 > a virtual drive with one file) Depending on your budget, I'd either give Cray or SGI a call, or build a cluster of AMD64 machines. You can get 16GB in a 1U chassis so that would reduce your requirements to around 700 machines, call it 18 racks minus the networking. You will not be able to use that as a ram disk and stripe it for a single machine to search. First, there's no way you'll be able to maintain any kind of uptime if you do that. With 5600 DIMMs, you'll lose at least one a week, probably more. Second, assuming you can completely process one 64-bit word per cycle and you had enough bandwidth you would need 625 seconds to process 10TB of data. What you will need to do is build a distributed application that a) allows processing to run on each machine and b) provides a mechanism for fault tolerance in the face of machine failures. You would do well to read up on the techniques used by google to manage unreliable systems and provide high-performance search. -- Brooks --=20 Any statement of the form "X is the one, true Y" is FALSE. PGP fingerprint 655D 519C 26A7 82E7 2529 9BF0 5D8E 8BE9 F238 1AD4 --JP+T4n/bALQSJXh8 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.1 (GNU/Linux) iD8DBQFBEROxXY6L6fI4GtQRAsE1AJ9UUeIiEVvvY/2cEd/CWKSrhXh1eQCeL+Qb keUyKiUQ59j7JdDyv3/punw= =zqLg -----END PGP SIGNATURE----- --JP+T4n/bALQSJXh8--
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