Date: Sat, 20 Jan 2001 01:26:00 -0600 From: "Jim C. Nasby" <jim@nasby.net> To: Mike Tancsa <mike@sentex.net> Cc: Sys Admin <admin@cb21.co.jp>, freebsd-stable@freebsd.org Subject: Re: RAID configuration for a mail server (1 or 5) Message-ID: <3A693D88.9D1F4E3D@nasby.net> References: <4.2.2.20010117193231.03731950@marble.sentex.net>
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Mike Tancsa wrote: > For speed, reliability and cost, have a look at the 4port 3ware card > (www.3ware.com) in RAID 10 config. Two RAID0 sets mirrored together. Get FWIW, a RAID0 of RAID1 sets is more desireable. When one of the drives fails, you only have to rebuild one drive, using it's mirrored counterpart. In the other case, you have to rebuild an entire RAID0 set from another set, tying up every drive in the system. Also, depending on how the mirroring is done, simultaneous failure of a drive on each mirror could render you without any data. While it would be really bad luck to lose two drives at once, the odds losing one on each mirror are far greater than losing both drives in a two-drive mirror that happens to be part of a stripe set. BTW, if memory serves, the downside that RAID 5 has over RAID 0 is that in order to update a segment of the set, you must first read the entire segment in, then recalculate it with the changed data, then write the changes back out. This will very often result in 2x the number of r/w operations as the number of drives. If you want more information, I suggest reading the excellent RAID overview at the vinum site. -- Jim C. Nasby (aka Decibel!) /^\ jim@nasby.net /___\ Freelance lighting designer and database developer / | \ Member: Triangle Fraternity, Sports Car Club of America /___|___\ Give your computer some brain candy! www.distributed.net Team #1828 Get paid to surf!! http://www.enteract.com/~nasby/alladvantage.html To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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