From mboxrd@z Thu Jan 1 00:00:00 1970 From: Goswin von Brederlow Subject: Re: If your using large Sata drives in raid 5/6 .... Date: Wed, 03 Feb 2010 12:25:16 +0100 Message-ID: <87zl3qv9wj.fsf@frosties.localdomain> References: <87f94c371002021440o3b30414bk3a7ccf9d2fa9b8af@mail.gmail.com> <87f94c371002021446y38dce6fds6acca2b4919ad773@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <87f94c371002021446y38dce6fds6acca2b4919ad773@mail.gmail.com> (Greg Freemyer's message of "Tue, 2 Feb 2010 17:46:25 -0500") Sender: linux-raid-owner@vger.kernel.org To: Greg Freemyer Cc: Linux RAID List-Id: linux-raid.ids Greg Freemyer writes: > All, > > I think the below is accurate, but please cmiiw or misunderstand. > > =3D=3D=3D > If your using normal big drives (1TB, etc.) in a raid-5 array, the > general consensus of this list is that it is a bad idea. =A0The reaso= n being > that the sector error rate for a bad sector has not changed with > increasing density. > > So in the days of 1GB drives, the likelihood of a undetected / > repaired bad sector was actually pretty low for the drive as whole. > But for today's 1TB drives, the odds are 1000x worse. =A0ie. 1000x mo= re > sectors with the same basic failure rate per sector. I just had such a case yesterday. It does happen too often. Esspecialy as drives get older. Rebuilding a raid5 becomes more and more dangerous as you increase drive capacity. > So a raid-5 composed of 1TB drives is 1000x more likely to be unable > to rebuild itself after a drive failure than a raid-5 built from 1 GB > drives of yesteryear. =A0Thus the current recommendation is to use ra= id > 6 with high density drives. If you can spare the drive and cpu then raid6 is definetly preferable. Although I think the only future is in combining the raid and filesyste= m into one. If you have some corrupted blocks then the FS can tell you which files are corrupted. Raid only really covers the case of a whole drive failing well. MfG Goswin -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html