On Sun, Nov 15, 2009 at 9:27 AM, Bob Friesenhahn <bfrie...@simple.dallas.tx.us> wrote: >> 3 x1TB and 2 x500GB disks. Is there any way the 2x500GB disks could be put >> into a stiped pool that could then be part of a 4 x1TB RAIDZ pool? > > I expect that you could use Solaris Volume Manager (DiskSuite) to stripe the > 2x500GB disks into a larger device, which could then be used as a single > device by zfs.
I wonder if a stripe or concat would be better for this use? If one drive failed, you could possibly read 1/2 the blocks for resilvering without waiting on a failed drive for every other block... Regardless, you are twice as likely to like the SVM volume as a native 1TB drive. Performance will probably be pretty good regardless of the type of SVM volume you use. There are a bunch of configurations you could use, depending on how much risk tolerance you have and whether you plan on upgrading drives later. The best option to get the most space and best protection would be to replace the 500GB drives with 1TB and do a 5x 1TB raidz. Creating two vdevs with a 3x 1TB raidz and a 2x 500GB stripe in one pool would give you 2.5TB of space and pretty good performance. This is probably the safest way to use your different drive sizes. You could also use mirrors for equally sized drives which would give you 1.5TB usable. The 3rd 1TB would not have any redundancy, but if you're comfortable with the risk, you could add it for 2.5TB. I would not recommend it however. This option would probably give you the best write performance, with or without the 3rd 1TB drive. Another option is to partition the 1TB drives, then create a 5x 500GB raidz pool and a second 3x 500GB pool. Two pools are not as flexible, but you could get away with single parity raidz, since losing a drive would only degrade one vdev per pool. Performance will probably suck since you are forcing the drive to seek a lot, but only when accessing both pools at the same time. You could also do the same partitioning and vdevs, but put them in one pool. You'd have the same fault tolerance as above, but one 3TB pool. This has less flexibility for replacing the 500GB drives, at least until vdev removal is available. performance would be slightly worse than above, since the drives will be doing more seeks. You could also partition your 1TB drives into 500GB pieces, then create a raidz of the 8 x 500GB partitions. If you have available ports and plan to upgrade or add devices in the near future, you can then replace the 500GB partitions with native devices. You'd need to do raidz2 (or higher) for protection, since losing one 1TB would be equivalent to losing 2 drives. This would give you 3TB usable, but until you replaced the partitions with real devices, you'd have less protection than raidz2 would normally afford. You'd still be better off replacing the 500GB drives and adding additional drives now and avoid migration and rebuilds later. -B -- Brandon High : bh...@freaks.com _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
