Date: Thu, 01 Jan 2004 17:59:18 -0500 From: Scott W <wegster@mindcore.net> To: Scott Mitchell <scott+freebsd@fishballoon.org> Cc: freebsd-questions@freebsd.org Subject: Re: What do you use? Message-ID: <3FF4A646.2020808@mindcore.net> In-Reply-To: <20040101224616.GA4891@tuatara.fishballoon.org> References: <3FF31E4B.1070305@edgefocus.com> <200312311706.25677.jbacon@mcw.edu> <3FF35827.8000500@edgefocus.com> <20040101114640.GB675@tuatara.fishballoon.org> <20040101130752.V65501@zoraida.natserv.net> <20040101224616.GA4891@tuatara.fishballoon.org>
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Scott Mitchell wrote: >On Thu, Jan 01, 2004 at 01:09:23PM +0000, Francisco Reyes wrote: > > >>On Thu, 1 Jan 2004, Scott Mitchell wrote: >> >> >> >>>As for RAID, we use Vinum, but only because I inherited a bunch of machines >>>with hot-swap SCSI bays and no hardware RAID. It works well, once you have >>>it set up, and I've even managed to swap out failed drives without a reboot >>>:-) I'll definitely investigate the 3ware cards when I need to build a new >>>RAID server, though. >>> >>> >>But wouldn't a 3ware RAID be slower than an SCSI setup? Unless your >>current setup is using old SCSI disks. Also how is the load? Lots of >>simultaneous use or just many quick/small access (ie people using >>documents/spreadsheets). >> >> > >There no particular reason for an ATA RAID to be slower than SCSI, assuming >similar disks in each. 10krpm 'server class' ATA disks are available these >days, although I don't know that anyone has done a 15krpm one yet. > Does SATA have tagged queing? (I don't know offhand if it does...?) I can guarantee modern SCSI throughput is superior to any of the SATA drives I've seen to date. Several of the 'hardware sites' (I think Tomshardware did a writeup on this or anadtech among others) agree with this statement as well. ATA specs tend to exaggerate their capabilities even worse than SCSI specs do- burst speeds are all fine and dandy, but not realistic at all in the real world. Meaning basically in short I wouldn't choose SATA over SCSI for a production server of any kind where speed was an issue. ATA has gotten better by far than it was speed-wise, and I'd be OK with it on a personal workstation for any purpose, but it's still playing catchup. >In any case, performance is only one reason to use RAID. My arrays are >RAID-5's, serving developer home directories over NFS, and a CVS server >(ie. lots of small file accesses). The main requirements were to have >some fault tolerance and to get the most out the of disks I could buy with >the available budget - hence the RAID-5. Read performance is no worse than >with a single disk, and degrades more gracefully with multiple simultaneous >access. Write performance is pretty awful, but that's the nature of >RAID-5. No doubt if I had an unlimited budget I would do things >differently, but those days are long gone :-( > Write performance is awful locally, or over NFS? NFS isn't exactly a speed demon. No comment on the unlimited budget as everyone at work just got (another) 'mandatory pay reduction'...but I do rememeber and miss those, $^#&*( ;-) Scott >I'd also expect/hope that a hardware solution (ATA or SCSI) would be easier >to manage. Vinum is great, but swapping out a dead drive is still a scary, >multi-step procedure, that I do infrequently enough that it always requires >half an hour with the manual and my notes from last time to make sure I get >it right. With our Windows servers (Compaq Proliants with hardware RAID), >you just yank the old drive, plug in the new one, and it's done. I'd love >to be able to do that with the FreeBSD servers as well. > > Scott > > >
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