April 17 2013 But first, a reading from the the book of man zpool: raidz raidz1 raidz2 raidz3 A variation on RAID-5 that allows for better distribution of parity and eliminates the "RAID-5 write hole" (in which data and parity become inconsistent after a power loss). Data and parity is striped across all disks within a raidz group. A raidz group can have single-, double-, or triple parity, meaning that the raidz group can sustain one, two, or three failures, respectively, without losing any data. The raidz1 vdev type specifies a single-parity raidz group; the raidz2 vdev type specifies a double-parity raidz group; and the raidz3 vdev type specifies a triple-parity raidz group. The raidz vdev type is an alias for raidz1. A raidz group with N disks of size X with P parity disks can hold approximately (N-P)*X bytes and can withstand P device(s) failing before data integrity is compromised. The minimum number of devices in a raidz group is one more than the number of parity disks. The recommended number is between 3 and 9 to help increase performance. The choices the SmartOS installer makes behind the scenes are reasonable, but can be altered if you wish to reconfigure after install, as the operating system is not on the physical drive set. OK, here are the defaults as installed: Tiny - Single SATA 250Mb HDD - ZFS no RAID [root@e0-cb-4e-0a-84-c1 ~]# zpool status pool: zones state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM zones ONLINE 0 0 0 c1t0d0 ONLINE 0 0 0 errors: No known data errors [root@e0-cb-4e-0a-84-c1 ~]# zpool list NAME SIZE ALLOC FREE EXPANDSZ CAP DEDUP HEALTH ALTROOT zones 232G 4.32G 228G - 1% 1.00x ONLINE - Small - 2x Matched SATA 1Tb or 2Tb HDD - MIRRORED (like RAID1) 1 Tb Drives: [root@2c-27-d7-2e-93-55 ~]# zpool status pool: zones state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM zones ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 c1d0 ONLINE 0 0 0 c2d0 ONLINE 0 0 0 errors: No known data errors [root@2c-27-d7-2e-93-55 ~]# zpool list NAME SIZE ALLOC FREE EXPANDSZ CAP DEDUP HEALTH ALTROOT zones 928G 4.32G 924G 8.44E 0% 1.00x ONLINE - 2 Tb Drives: root@3c-d9-2b-50-d3-d9 ~]# zpool status pool: zones state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM zones ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 c1d0 ONLINE 0 0 0 c2d0 ONLINE 0 0 0 errors: No known data errors [root@3c-d9-2b-50-d3-d9 ~]# zpool list NAME SIZE ALLOC FREE EXPANDSZ CAP DEDUP HEALTH ALTROOT zones 1.81T 4.32G 1.81T 1.16E 0% 1.00x ONLINE - Large - 16x Matched SAS 3Tb - RAIDZ1 (Like RAID5) [root@00-25-90-93-a3-2a ~]# zpool status pool: zones state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM zones ONLINE 0 0 0 raidz1-0 ONLINE 0 0 0 c0t1d0 ONLINE 0 0 0 c0t1d1 ONLINE 0 0 0 c0t1d2 ONLINE 0 0 0 c0t1d3 ONLINE 0 0 0 c0t1d4 ONLINE 0 0 0 c0t1d5 ONLINE 0 0 0 c0t1d6 ONLINE 0 0 0 c0t1d7 ONLINE 0 0 0 c0t2d0 ONLINE 0 0 0 c0t2d1 ONLINE 0 0 0 c0t2d2 ONLINE 0 0 0 c0t2d3 ONLINE 0 0 0 c0t2d4 ONLINE 0 0 0 c0t2d5 ONLINE 0 0 0 c0t2d6 ONLINE 0 0 0 c0t2d7 ONLINE 0 0 0 errors: No known data errors [root@00-25-90-93-a3-2a ~]# zpool list NAME SIZE ALLOC FREE EXPANDSZ CAP DEDUP HEALTH ALTROOT zones 43.5T 5.68G 43.5T - 0% 1.00x ONLINE - Un-Mirror: Simple zpool Example For an example of reconfiguring SmartOS I un-mirror-ed the default zone in my system with 2x 1Tb disks, removing one disk from the mirror for more space, and adding it back without mirroring, so it presents 2Tb without redundancy. Starting state: [root@2c-27-d7-2e-93-55 /]# zpool status pool: zones state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM zones ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 c1d0 ONLINE 0 0 0 c2d0 ONLINE 0 0 0 errors: No known data errors [root@2c-27-d7-2e-93-55 ~]# zpool list NAME SIZE ALLOC FREE EXPANDSZ CAP DEDUP HEALTH ALTROOT zones 928G 4.32G 924G 8.44E 0% 1.00x ONLINE - Detach the second mirrored drive (vdev c2d0): [root@2c-27-d7-2e-93-55 /]# zpool detach zones c2d0 [root@2c-27-d7-2e-93-55 /]# zpool status pool: zones state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM zones ONLINE 0 0 0 c1d0 ONLINE 0 0 0 errors: No known data errors [root@2c-27-d7-2e-93-55 /]# zpool list NAME SIZE ALLOC FREE EXPANDSZ CAP DEDUP HEALTH ALTROOT zones 928G 4.32G 924G 8.44E 0% 1.00x ONLINE - Add the drive back to the zones zpool: [root@2c-27-d7-2e-93-55 /]# zpool add zones c2d0 [root@2c-27-d7-2e-93-55 /]# zpool status pool: zones state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM zones ONLINE 0 0 0 c1d0 ONLINE 0 0 0 c2d0 ONLINE 0 0 0 errors: No known data errors [root@2c-27-d7-2e-93-55 /]# zpool list NAME SIZE ALLOC FREE EXPANDSZ CAP DEDUP HEALTH ALTROOT zones 1.81T 4.32G 1.81T 8.44E 0% 1.00x ONLINE - So - two commands to change the default to un-mirrored and full use of the available disk space without redundancy. |
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