From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joachim Otahal Subject: Re: RAID0 on disks with different sizes Date: Mon, 15 Mar 2010 07:45:53 +0100 Message-ID: <4B9DD7A1.5060603@gmx.net> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: rj Cc: Mdadm List-Id: linux-raid.ids rj schrieb: > Hi, > > How does MD RAID0 layer support disks with different sizes? > All PARTITIONS to create a RAID0 device should be the same size, else the smallest is the one that counts. If you have 250GB+500GB+750GB: Create RAID0 with threee drive using the space from 0-250 GB, then a RAID1 with the space from 251 to 500, and the last one just normal (or linear). You can combine them with LVM. You _could_ create 6 partitions with 250 GB and create a RAID0 across all of them, but that will hurt the performance a lot. Best for all in one RAID is possible with "linear" = JBOD. > 1. Does it take the size of smallest disk and do the striping > accordingly? This way there would be wastage of space in bigger > disks. > Or > 2. Does it stripe across all the space of disks? This way, if striping > is not possible for a disk because it has exhausted the space, > striping will continue or remaining devices (although with > compromising performance for these stripes because they have one disk > less). > > What approach md chooses? Also, what approach is taken for RAID5 in such cases? > md does not choose on it's own, you set it up. When using disks like the example above: RAID 5 across the spave of 0-250 GB. > Thanks in advance. > -- > 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 http://vger.kernel.org/majordomo-info.html > >