Date: Sat, 22 Jan 2005 10:00:52 +0100 From: Stijn Hoop <stijn@win.tue.nl> To: Ted Mittelstaedt <tedm@toybox.placo.com> Cc: FreeBSD Questions <freebsd-questions@freebsd.org> Subject: Re: Hardware RAID Message-ID: <20050122090052.GG35557@pcwin002.win.tue.nl> In-Reply-To: <LOBBIFDAGNMAMLGJJCKNGEBMFAAA.tedm@toybox.placo.com> References: <20050121090216.GC31548@pcwin002.win.tue.nl> <LOBBIFDAGNMAMLGJJCKNGEBMFAAA.tedm@toybox.placo.com>
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--p2kqVDKq5asng8Dg Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Jan 21, 2005 at 11:42:32PM -0800, Ted Mittelstaedt wrote: > Stijn Hoop said: > > "Ted Mittelstaedt" <tedm@toybox.placo.com> said: > > > This did teach me a lesson that I kind of knew already but > > > didn't think too much about. That is, a software array > > > is no substitute > > > for a hardware array. ... > > > > I respectfully disagree here; it is a substitute in some respects, > > especially if you factor in cost. >=20 > I think you didn't read my post, Well I tried to... > I explicitly stated vinum is a great > thing if what your wanting to do is use a bunch of cheap disks and > cheap controller cards to either get a giant partition, or to > stripe them together and get faster access. Yes, but that's what I was refuting in part; I've used it for reliability purposes to great effect, as I stated. So IMHO it's also a great thing if you need reliability for a lower price. > In other words cost is the only justification for selecting software > raid over hardware raid. You haven't really made the case that vinum > is better than a hardware array card on any other issue except cost. It was not my intent to describe vinum as being 'better' than the hardware RAID. As I read it, you dismissed software RAID for reliability purposes. I was stating that it can be used for that purpose. > > My vinum volumes allowed me to survive for a long time without backups > > (bad idea, don't do that), and for the past years have allowed me to > > survive without having to restore my backups. This through about 5 > > failing ATA disks and multiple upgrades of the storage space. > > > > I'd say it was worth it for me, including reliability. > > > > If you need speed, or have the cash, etc, you can go for hardware > > RAID. But even there I've seen and heard horror stories of > > incompatible disks, spontaneously lost configurations or even worse, > > silent data corruption due to a bad disk. >=20 > I didn't say these things couldn't happen on a hardware array. I > said that when these things do happen, it's worse for a software > array than a hardware array, and that they happen a lot more on a > software array. In my experience, when bad things happen, it was the same for the software RAID arrays as for the hardware RAID arrays. Regular vinum does have a few warts (notably, online rebuilding is b0rked) but other than that it's the same procedure: remove bad drive, add new drive, rebuild. I agree that I've seen more failures with software RAID than hardware RAID. And certainly cost is a factor in that. It still comes down to cost vs downtime. The only thing I 'objected' to in your post was the fact that you dismissed vinum as being useful in reliability situations. I hope I made that clearer this time. --Stijn --=20 "Well," Brahma said, "even after ten thousand explanations, a fool is no wiser, but an intelligent man requires only two thousand five hundred." -- The Mahabharata. --p2kqVDKq5asng8Dg Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (FreeBSD) iD8DBQFB8hZEY3r/tLQmfWcRAmRGAJ9rJnO7sSndB7O7LHIb2T4DABEnNACeNFj4 Px9Bnh20z4YxQcUPDvH3sZs= =ouNw -----END PGP SIGNATURE----- --p2kqVDKq5asng8Dg--
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