Hugo Mills wrote: > On Thu, Apr 18, 2013 at 02:45:24PM +0100, Martin wrote: >> Dear Devs, <snip> >> Note that esata shows just the disks as individual physical disks, 4 per >> disk pack. Can physical disks be grouped together to force the RAID data >> to be mirrored across all the nominated groups? > > Interesting you should ask this: I realised quite recently that > this could probably be done fairly easily with a modification to the > chunk allocator. <snip>
One thing that might be an interesting approach: Ceph is already in mainline, and uses CRUSH in a similar way to what's described (topology-aware placement+replication). Ceph does it by OSD nodes rather than disk, and the units are objects rather than chunks, but it could potentially be a rather good fit. CRUSH does it by describing a topology hierarchy, and allocating the OSD ids to that hierarchy. It then uses that to map from a key to one-or-more locations. If we use chunk ID as the key, and use UUID_SUB in place of the OSD id, it could do the job. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
