From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Clements Subject: Re: accessing windows raid with mdadm? Date: Sat, 04 Nov 2006 11:53:57 -0500 Message-ID: <454CC5A5.4030202@steeleye.com> References: <1162419372.4743.6.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1162419372.4743.6.camel@localhost.localdomain> Sender: linux-raid-owner@vger.kernel.org To: Shaya Potter Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids Shaya Potter wrote: > [please cc: me on responses] > > if one read Documentation/fs/ntfs.txt in the linux kernel, it talks > about accessing windows raid volumes in Linux > > If one is using non raid-5, one can use the device mapper, but if one is > using raid-5, one has to use the md driver. > > However, it seems to be about using raidtools (raidtab and the like). > Can anyone who understand raidtools and mdadm translate the instructions > to mdadm, as that would seem to be what most of us use today? The biggest thing here is that, since Windows stores its RAID information in this LDM area, which is outside the partitions themselves, there is no room for an md superblock at the end of each partition (even if the RAID information was on each partition, it's doubtful there would be room for an md superblock). So you have to assemble the array without superblocks, or else the md superblocks will overwrite data. There is currently no way to "Build" (i.e., assemble an array without using superblocks) a raid5 array using mdadm. I don't know if raidtools would allow that or not. Building arrays without superblocks is generally risky (since device states and roles are not persistently tracked) for anything other than simple non-RAID arrays, or read-only access to your data. -- Paul