On Wed, October 13, 2010 2:46 pm, [email protected] wrote: > On Wed, Oct 13, 2010 at 01:51:22PM -0400, Chris Knadle wrote: >> >> On Wed, October 13, 2010 7:52 am, Matthias Johnson wrote: >> > Yeah sorry. I meant to say fdisk -l shows the raid as this disk >> doesn't >> > contain a valid partition table. Thinking about it more I think I >> > understand. I guess that since software raid works by creating a >> virtual >> > device and existing in /dev fdisk attempts to read this along with the >> > individual disks but the md disks it does not understand. Seems >> pretty >> > obvious now. >> > >> > Matthias Johnson >> >> You might be correct, but it doesn't sound right. Last I recall making >> a >> mirrored disk using md raid, I had md mirroring filesystems that were on >> /partitions/ on both disks. So as far as I recall, md works with >> partitions. The instructions I just looked up for mdadm and Linux >> software raid showed using md with partitions. It's apparently possible >> to set up raid using the raw disk device, though -- but doing so seems >> to >> be not recommended. > > Yes, you can set it up (like anything in linux) on a partition or on a > raw disk. Linux doesn't care what sort of block device it is. > > I, too, always preferred partition. Setting it up on a partition lets > you a) flag the partition as being part of a raid and b) I believe it > helps the kernel autoraid detection.
The complaint against using a raw disk seems to be that it can cause an issue with Linux getting confused because the partition table contains data rather than a partition table. http://www.seedsofgenius.net/uncategorized/linux-software-raid-tips/comment-page-1 This also explains something else; if you want to be able to /boot/ off of a RAID drive, I think you must use partitions, because otherwise the MBR might contain data instead of an MBR area. -- Chris -- Chris Knadle [email protected] _______________________________________________ Mid-Hudson Valley Linux Users Group http://mhvlug.org http://mhvlug.org/cgi-bin/mailman/listinfo/mhvlug Upcoming Meetings (6pm - 8pm) MHVLS Auditorium Nov 3 - Open Source Hardware: Bugs, Beagles and Beyond Dec 1 - IBM's Open Client Deployment Jan 5 - Building a Comunity Site with Drupal
