Jeff Bonwick wrote: > Using ZFS to mirror two hardware RAID-5 LUNs is actually quite nice. > Because the data is mirrored at the ZFS level, you get all the benefits > of self-healing. Moreover, you can survive a great variety of hardware > failures: three or more disks can die (one in the first array, two or > more in the second), failure of a cable, or failure of an entire array. > > Jeff > > On Sat, Jun 14, 2008 at 08:09:49AM -0700, zfsmonk wrote: > >> Mentioned on >> http://www.solarisinternals.com/wiki/index.php/ZFS_Best_Practices_Guide is >> the following: >> "ZFS works well with storage based protected LUNs (RAID-5 or mirrored LUNs >> from intelligent storage arrays). However, ZFS cannot heal corrupted blocks >> that are detected by ZFS checksums." >> >> based upon that, if we have LUNs already in RAID5 being served from >> intelligent storage arrays, is it any benefit to create the zpool in a >> mirror if zfs can't heal any corrupted blocks? Or would we just be wasting >> disk space? >> As Jeff mentioned, use two HW RAID-5 LUNs in a zpool for a mirror (or, even 3+ LUNs for a RAID-Z of RAID-5 :-)
The quote from the Best Practices Guide is applicable to single LUN zpools (and, applies to any single-vdev zpool). Indeed, there are some nasty problems with using single-LUN zpools, so DON'T DO IT. ZFS is happiest (and you will be too) when you allow some redundancy inside ZFS, and not just at the hardware level. -- Erik Trimble Java System Support Mailstop: usca22-123 Phone: x17195 Santa Clara, CA Timezone: US/Pacific (GMT-0800) _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
