From kragen@dnaco.net Thu Sep 10 17:48:44 1998 Date: Thu, 10 Sep 1998 17:48:42 -0400 (EDT) From: Kragen To: Josip Loncaric cc: Beowulf mailing list Subject: Re: RAID controller question... In-Reply-To: <35F82FEA.EE2B5EB1@icase.edu> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Keywords: X-UID: 1814 Status: O X-Status: On Thu, 10 Sep 1998, Josip Loncaric wrote: > Greg Lindahl wrote: > > As usual, generalizations lead you astray. If you want to hook 10+ > > drives to a machine and are seek limited, UIDE won't do it for you, > > even if your sustained bandwidth is much lower than 20 MB/s. Think > > database. Sure, that means you spend more money. > > I thought that the idea of the original Beowulf was to use many > processors with a disk or two per CPU, with the goal of achieving bigher > aggregate bandwidth than the alternative configuration of many disks per > CPU. The Vesta distributed filesystem from IBM did this. I'm curious if anyone has done this with Linux machines -- Vesta was for an SP. Is it possible to use the new "access raw disk across a network" facility in Linux 2.1 (does it exist or is it a rumor?) along with the md drivers to begin to simulate this? Such an approach would also provide some amount of redundancy -- although the machine running the md driver would appear to be an SPOF, there could be a backup machine prepared to run the md driver as soon as the current master failed, and start fscking. This would have no SPOF, except that fscking a huge disk takes forever. (Pray for journaling in ext2!) Vesta was superior in this regard, because it did not have a single point of failure (for performance reasons) -- the clients had to figure out what machines to talk to to get their files. Kragen (who hasn't used Vesta, the md driver, two-tailed SCSI disks, or even Linux 2.1) -- Kragen Sitaker I don't do .INI, .BAT, .DLL or .SYS files. I don't assign apps to files. I don't configure peripherals or networks before using them. I have a computer to do all that. I have a Macintosh, not a hobby. -- Fritz Anderson