From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Evans Subject: Re: Booting from RAID1 Date: Sun, 20 Dec 2009 16:39:04 -0800 Message-ID: <4877c76c0912201639q6afb2c36m6eb374f87d5188fc@mail.gmail.com> References: <4877c76c0912200115q4c91512cj119ff23f7d662d16@mail.gmail.com> <67.C8.01567.DC44E2B4@cdptpa-omtalb.mail.rr.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <67.C8.01567.DC44E2B4@cdptpa-omtalb.mail.rr.com> Sender: linux-raid-owner@vger.kernel.org To: Leslie Rhorer Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Sun, Dec 20, 2009 at 7:37 AM, Leslie Rhorer wr= ote: >> >> Oh, and you'll also very likely want grub to read the /boot >> >> filesystem, which is why it must be on a partition followed by th= e >> >> raid header, instead of a partition containing a raid header and = raid >> >> protected partition. =A0That use is OK since grub operates read-o= nly. >> > >> > =A0 =A0 =A0 =A0I think I follow you, here. =A0IOW, partition the d= rive, create the >> md >> > target, and then format the RAID array, right? =A0Or are you sayin= g one >> should >> > format the partition and then create the RAID array on top of it? >> > >> > >> >> It works much more cleanly if you create the RAID array first, and >> then use the container it provides; > > =A0 =A0 =A0 =A0Now I definitely don't follow you. =A0Are you saying o= ne should create > an array from the raw drive, partition it, format the first partition= , then > create secondary arrays from the second and third partition, and fina= lly > format the second and third array? > >> this way the end of your file-system does not overlap the raid super= - >> block. > > =A0 =A0 =A0 =A0I can follow that - there's a danger of wiping or movi= ng the mdadm > superblock if it is contained in the filesystem, but it seems to me > partitioning the drive and then creating the array from a partition, = as I > first suggested, will accomplish that just fine. > > It is an option to partition it after the fact; however generally it's better to partition it first, and then apply whatever raid level you like to each partition. You misunderstand on the second half; the danger is that both the 'filesystem' and 'mdadm superblock' attempt to use the whole device. That may appear to work for a while, but there is danger that the filesystem could grow and store data in the same place the mdadm superblock is; depending on if the filesystem or mdadm then filesystem within the device was used this will either fail, or destroy the raid information block. -- 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