On 2012-06-05, at 10:12 AM, David Shaw wrote: > I've been looking around, but can't seem to find an authoritative statement on setting stride and stripe-width for RAID 50 (i.e. a RAID 0 over multiple RAID 5s) > > Based on my understanding of what stride and stripe-width set, it seems to me that it should be calculated the same as it would be if there were no multiple-level RAIDing involved. For example, given a RAID 50 made up of two 3+1 RAID 5s striped together (so 8 disks total) with a 512k chunk size and 4k block size, the stride should be 128 (512 / 4) and the stripe-width should be 768 (stride * 6 data disks). Strictly speaking, you only need a stripe-width of 384 (stride * 3 data disks) since this is the minimum read-modify-write boundary. That said, why not configure your system with RAID-6 6+2? This gives better fault tolerance than RAID-5. > These settings should work equally well whether the two RAID 5s are striped together or just appended one after the other via LVM. > > Is my reasoning correct? > > David > > > _______________________________________________ > Ext3-users mailing list > Ext3-users@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/ext3-users Cheers, Andreas _______________________________________________ Ext3-users mailing list Ext3-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ext3-users
