Date: Fri, 23 Nov 2007 10:25:26 +0100 From: "Jan Catrysse" <j.catrysse@proximedia.be> To: <freebsd-questions@freebsd.org> Cc: 'Bill Moran' <wmoran@potentialtech.com> Subject: RE: RAID1 synchronisation - howto OR not necessary? Message-ID: <20071123092146.E0E1B2878E@smtp.proximedia.com> In-Reply-To: <20071122155640.fa7e0536.wmoran@potentialtech.com>
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> From: Bill Moran [mailto:wmoran@potentialtech.com]=20 > Sent: Thursday, November 22, 2007 9:57 PM > To: Jan Catrysse > Cc: freebsd-questions@freebsd.org > Subject: Re: RAID1 synchronisation - howto OR not necessary? >=20 > "Jan Catrysse" <J.Catrysse@proximedia.be> wrote: > > > > Dear subscribers, > >=20 > > I am currently running a production server: > > FreeBSD 6.2 STABLE > > Onboard Intel ICH8R Raid 1 with 2x SATA300 500GB HDD Using ATA for=20 > > Raid1 > >=20 > > On Windows systems it is an absolute must to do a Raid=20 > Synchronisation=20 > > every once and a while to maintain data consistency. >=20 > Wow. Any RAID controller with that requirement is junk. =20 > Where did you get the information from that you had to=20 > synchronize? Does it say so in the manual? Does it actually=20 > say "every once and a while" or does it give a specific schedule. >=20 > I suspect that you have wrong information ... but if your=20 > information is correct, I'd get a refund on that RAID controller. >=20 > > I am some what disturbed that that kind of command / tool seems not=20 > > available on FreeBSD. >=20 > There is not, because such a thing should not be necessary. >=20 > > Are there other methods to do the synchronisation? > > 1) Maybe atacontrol detach & atacontrol addspare &=20 > atacontrol rebuild? > > 2) Maybe data consistency is always maintained automatically by the=20 > > driver? > > 3) Maybe I have to panic and urgently make backups? >=20 > If resyncing your raid on a regular basis is truly a=20 > requirement, I'd do > #3 at least, followed by getting my money back. Hi Bill, Thank you for your input. I assumed this was common knowledge, but I can be wrong? I've checked some other RAID controllers in the company and all of them = have the need to be verified/synchronized once and a while. This happens = in the BIOS for the more expensive cards (> 600=E2=82=AC) and with a = utility/driver for the low budget cards... In my case I am using a real inexpensive onboard Intel ICH8R controller = but I presume even a low cost controller needs to do the job done. = Furthermore it's only a simple mirror... Intel provides a small windows = utility to synchronize. This is what I found in a 3Ware manual: Verification can provide early warning of a disk drive problem or = failure. ...verification once every 24 hours... Not verifying the unit periodically can lead to an unstable array unit = and may cause data loss. It is strongly recommended that you schedule a verify at least 1 time = per week. For a RAID 1 or RAID 10 unit, a verify compares the data of one mirror = with the other. For RAID 5, RAID 6, and RAID 50, a verify calculates = parity and compares it to what is written on the disk drive. Cheers, Jan
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