From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roman Mamedov Subject: Re: Can't reshape RAID1 to RAID5 due to chunk size Date: Wed, 19 Sep 2012 13:46:01 +0600 Message-ID: <20120919134601.0671d75f@natsu> References: <20120912105956.155f5d5e@natsu> <20120919162058.3101366d@notabene.brown> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/24/3NvmYNkI6kwYffM2XDNa"; protocol="application/pgp-signature" Return-path: In-Reply-To: <20120919162058.3101366d@notabene.brown> Sender: linux-raid-owner@vger.kernel.org To: NeilBrown Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids --Sig_/24/3NvmYNkI6kwYffM2XDNa Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Wed, 19 Sep 2012 16:20:58 +1000 NeilBrown wrote: > What you need to do is: > - make sure the filesystem in /dev/md1 doesn't use the last 3k (it prob= ably=20 > uses a 4K block size, so cannot use that last bit > - resize the array down to 488372860K (mdadm -G /dev/md0 --size 488372= 860) > - convert to a 2-device RAID5 with a 4K chunk size: > mdadm -G /dev/md1 -c 4K -l5 -n2 > - convert to a 3-device RAID5 with a 64K chunk size: > mdadm -G /dev/md1 -c 64k -n3 >=20 > NeilBrown Thanks, Neil. I have since finished this migration in another way, luckily I had some spa= re drives lying around, so had an option to create a separate RAID5 from scrat= ch and move over & replace the drives one by one. By the way the "want_replacement" feature is totally awesome, thanks to it = at no point in my operations I was left without redundancy (after all a N-disk degraded RAID5 reliability-wise is like a RAID0 of N disks, and that's something I wanted to avoid having even for a short period). --=20 With respect, Roman ~~~~~~~~~~~~~~~~~~~~~~~~~~~ "Stallman had a printer, with code he could not see. So he began to tinker, and set the software free." --Sig_/24/3NvmYNkI6kwYffM2XDNa Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iEYEARECAAYFAlBZeDkACgkQTLKSvz+PZwgkYQCfUy/WnL9H9kC1Sc1FFw7425dW qcMAnAjwa7p1y8USSdKAeJM8dVhQEgPQ =iz6U -----END PGP SIGNATURE----- --Sig_/24/3NvmYNkI6kwYffM2XDNa--