From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?Q?Mathias_Bur=C3=A9n?= Subject: Re: Growing 6 HDD RAID5 to 7 HDD RAID5 Date: Tue, 12 Apr 2011 18:21:13 +0100 Message-ID: References: <20110412231401.5bb9065c@natsu> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20110412231401.5bb9065c@natsu> Sender: linux-raid-owner@vger.kernel.org To: Roman Mamedov Cc: Linux-RAID List-Id: linux-raid.ids On 12 April 2011 18:14, Roman Mamedov wrote: > On Tue, 12 Apr 2011 17:56:05 +0100 > Mathias Bur=C3=A9n wrote: > >> I'm approaching over 6.5TB of data, and with an array this large I'd >> like to migrate to RAID6 for a bit more safety. > > That's a great decision (and I suppose you made a typo in the subject= ). > RAID5 is downright dangerous at that disk count, and with disks of th= at size. > >> I'm just checking if I >> understand this correctly, this is how to do it: >> >> * Add a HDD to the array as a hot spare: >> mdadm --manage /dev/md0 --add /dev/sdh1 >> >> * Migrate the array to RAID6: >> mdadm --grow /dev/md0 --raid-devices 7 --level 6 > > Looks correct to me... > > The first command can be just "mdadm --add /dev/md0 /dev/sdh1". > > If you'd rather avoid a reshape at this point, you can add > "--layout=3Dpreserve" to the second line. That way you will have just= a rebuild > of the new drive, instead of a full reshape. > > You will also need to "--grow --bitmap=3Dnone" first (you can re-add = the bitmap > later). > > -- > With respect, > Roman > Hi, Yep I mean RAID6, stupid subject line. If I use --layout=3Dpreserve , what impact will that have? Will the array have redundancy during the rebuild of the new drive? If I preserve the layout, what is the final result of the array compared to not preserving it? Cheers, // Mathias -- 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