From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Evans Subject: Re: RAID 5 build time optimization question and experiments. Date: Fri, 11 Dec 2009 14:35:22 -0800 Message-ID: <4877c76c0912111435o5a79dfccs2a27b48128150921@mail.gmail.com> References: <4B227932.80503@mpstor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Fri, Dec 11, 2009 at 8:57 AM, Cat'Killer wrote= : >> On Fri Dec 11, 2009 at 02:55:31PM +0000, Cat'Killer wrote: >> >>> I found a way using Doug Gilbert's great sg3utils to zero all these >>> disks in a very efficient manner, using sgp_dd, at near drive >>> bandwidth, and proceeded to zero all the disks fully in about 4 hou= rs! >>> >>> Once done, I then created a RAID 5 on 10 disks, waited for the rebu= ild >>> to complete, stopped the array using mdadm, and dumped each of the >>> RAID's components superblocks to files. >>> >> <-snip-> >>> >>> The create worked fine and I waited for the rebuild to be complete >>> before stopping the array and dumping the SBs. >>> >>> I then proceeded to write these same superblocks to 10 new similar >>> disks in a different system. >>> >> You could just do the create with --assume-clean, which should take = very >> little time at all. =A0If the drives were zeroed initially then this= will >> give you valid parity data. >> > Thank you for this, that's exactly what I was looking for. I had > looked in the manpage beforehand but I did not search for the right > terms nor assumed this would work in case of an array created ontop o= f > zeroed drives. > > Thanks again. > > Ben. > >> Cheers, >> =A0 Robin >> >> -- >> =A0 =A0___ =A0 =A0 =A0 =A0 =A0 ( ' } =A0 =A0 | =A0 =A0 =A0 Robin Hil= l =A0 =A0 =A0 =A0 >> | >> =A0/ / ) =A0 =A0 =A0| Little Jim says .... =A0 =A0 =A0 =A0 =A0 =A0 =A0= =A0 =A0 =A0 =A0 =A0 =A0 =A0| >> =A0// !! =A0 =A0 =A0 | =A0 =A0 =A0"He fallen in de water !!" =A0 =A0= =A0 =A0 =A0 =A0 =A0 =A0 | >> >> >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid"= in > the body of a message to majordomo@vger.kernel.org > More majordomo info at =A0http://vger.kernel.org/majordomo-info.html > Yes, I had just come to a similar conclusion in a recent email series and even provided a patch against the git copy of the manpage to clarify the documentation. -- 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