From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?Q?Micha=C5=82?= Sawicz Subject: Re: Best strategy to incrementally replace smaller HDDs Date: Fri, 09 Sep 2011 16:12:36 +0200 Message-ID: <1315577572.14468.11.camel@michal-laptop> References: <1315565285.2291.25.camel@michal-laptop> Mime-Version: 1.0 Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-zeZJsAMiTGEAhi+i1KZZ" Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: David Brown Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids --=-zeZJsAMiTGEAhi+i1KZZ Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Dnia 2011-09-09, pi=C4=85 o godzinie 14:34 +0200, David Brown pisze: > On 09/09/2011 12:48, Micha=C5=82 Sawicz wrote: > > Hi all, given the configuration below: > > * 8 x 1TB HDDs > > * 2 x 2TB HDDs > > > > On which I currently have: > > * (10 x 1TB) RAID6 - persistent storage > > * (2 x 1TB) system / temporary storage etc. > > >=20 > By this do you mean that you have 8 x 1TB drives with a 1 TB partition= =20 > on each, and 2 x 2T drives with 2 x 1TB partition on each? So that the= =20 > two big disks are shared with both raids? Yes, that wasn't like that before, but that's a result of exchanging two 1TB drives to 2TB ones.=20 > > I want to replace the 1TB drives for 2TB ones on an as-needed basis, > > what strategy would you recommend? >=20 > This sounds like you are thinking that you can replace a single disk in= =20 > your RAID6 array and get more storage - changing 10 x 1 TB raid6 =3D 8TB= =20 > into 9 x 1TB + 1 x 2TB raid6 =3D 9 TB. It doesn't work like that. You= =20 > will have to replace /all/ your 1 TB devices with 2 TB devices (and move= =20 > the second raid off the two existing 2TB devices) - all members of the= =20 > raid6 must be the same size. Actually no, I know how RAIDs work, so the three schemes I described below account for that. > To help you plan your upgrades, it is also useful to know your=20 > partitioning scheme (for example, do you use LVM?), whether you have the= =20 > space to put lots more drives in the system or must do it one drive at a= =20 > time, whether you can take the system off-line during the process, and= =20 > whether you need to do the upgrade quickly or can spend a week or so at= =20 > it (some of these are conflicting requirements). No LVM here. The most important - big RAID6 - is a single partition. The remaining 2 x 1TB on the big drives are split into RAID1 for boot, RAID10 for root, RAID0 for temporary storage and swap space. I can temporarily put more drives in there. I can take it off-line for some periods and I can do the upgrade over an extended period of time.=20 > Before you think about upgrading, however, make sure you have a solid=20 > backup. Then make sure you have a backup of that backup - and a plan=20 > for how to restore everything if something goes horribly wrong. Yeah... I plan to rely on RAID's redundancy by moving data around, growing / shrinking the filesystems and then shuffling the HDDs. I know that's asking for trouble, but I haven't yet found a place to rent 8TBs of storage for a week... And that's worked for me in the past, btw. Twice, even, IIRC. --=20 Micha=C5=82 (Saviq) Sawicz --=-zeZJsAMiTGEAhi+i1KZZ Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iQIcBAABAgAGBQJOah7UAAoJEGnv7NPGHSZFr4gP/R1SMqdQ5tvAIoaAvfiiUTUh t+63PUdaooAe6fncGEnQ56jDf0CwnbexQugaFE1OctWHzvzBK1sDAqabg7Kr3Nu8 HWpUVI3ELKdDep3dS0GXkvX1C3STuHY+uZYPSjr3Wl/9K+Gc8r8huHcMbwXaANK7 D5c1GmmGjf/XpONl+gzkHVl+v0XEBjm2HtTBmhZ6jniAsRkymFl5m6j5JwM/W3SJ LweygFetcigarVPwyaFsieB4zyksL8aaBscBsL4XhhcDI7FUq4Ur5wrXo3Dv0zU6 8B1jP0k1CQM37twuuxdHxcW9Uu9DSC28O/C9SdnX4xe1RgcWjsveolZecLL6up3X haSYSDl+vy5JAKQOSyYZAtjV9FtgJiJcBF5owFcmlI/h4H75swOj+X5WrGpbU4RX bNEig6v0Ihwo1W4dcyK6ggH02LL8h2iLImaCUSn3npqwLvSJPN2gAObrC5Zvd1pG nYxEzOHmWfWoXOHLQhkSM4GtIEf6plyxh5kMylnMTTiBaEsE0YFvbvRb0nTMa885 7pt8BR2W9GsgeHA6lTG7l0sJUaFkf+mhRnnEOr4IBPA3XPBY6fAhGw3Jrfurg1vc a9A+Y9d1wBPfK7ziKcsRjZXshgKjuyrRO3LRzooS+WsXd5dKzUeI0nbvAT7kRkxZ v7ZGK5jsTjpA6WghLUim =km5Q -----END PGP SIGNATURE----- --=-zeZJsAMiTGEAhi+i1KZZ--