Date: Tue, 3 Mar 1998 17:28:48 -0800 (PST) From: Tom <tom@sdf.com> To: Omar Thameen <omar@clifford.inch.com> Cc: shimon@simon-shapiro.org, freebsd-hardware@FreeBSD.ORG Subject: Re: getting oriented with RAID Message-ID: <Pine.BSF.3.95q.980303171951.8576A-100000@misery.sdf.com> In-Reply-To: <19980303200705.12976@clifford.inch.com>
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On Tue, 3 Mar 1998, Omar Thameen wrote: > I really want to make sure I understand the implementation of RAID > on freebsd, because it looks like a great thing to have on production > servers. Sorry if this continues to be very basic. Sorry, there is no "implementation of RAID on freebsd". RAID is handled by the controller. FreeBSD just sees a big disk. > First say I have a total of four 2G drives. I want to mirror them for > redundancy, so I have 2x2G available space (I guess they would be > called /dev/dpt0 and /dev/dpt1). Now say I want to optimize > reads and writes, so I use ccd and make the 2x2G (mirrored) drives into > one 4G drive, /dev/ccd0. If one of the mirrored drives goes bad, > am I then able to power down the machine, replace the bad drive, > then have the dpt manager perform its magic to recreate the data? > Is ccd none the wiser? Yes. If you setup a hotstandy, you don't even need to shutdown. A native FreeBSD dpt manager (if available) would allow you to do everything without shutting down. Mirrors already optimize reading, as you can read from both drives in parallel. That may be enough for your application. Probably better off using RAID5, and get a 5th disk. You end up with 8 GB of usable space. > Second, I see that the "Entry Level" DPT RAID controllers run on > a 68000 processor, while the "High Performance" ones use a 68040. > In what types of applications does this become a factor? In the > above system, I'm talking about a heavily hit pop3 or web server. I've only used the PM334UW, but it is on a mail server. Tom To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message
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