I recently expanded my storage pool "zstorage" by adding two more drives. It had 3 3TB drives in RAID-Z, and I added two more 1.5TB drives also in RAID-Z (which I understand is effectively the same as mirroring). I know it's not the most efficient setup, but these are the drives I had. I expect that with parity, I should get to use 6TB from the first set and 1.5TB from the second for 7.5TB total.
After the add, everything looks fine, and from the commands below, you can see that there is now more space listed by zpool list, and the drives show up as I would expect with zpool status. However, the amount of disk space available did not increase, as you can see below.
Any idea why I did not get more disk space out of this? I seem to have gained nothing from adding the two 1.5TB drives.
kevin@atlas:~$ sudo zpool list
NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT zstorage 10.8T 7.79T 3.05T 71% 1.00x ONLINE -
kevin@atlas:~$ sudo zfs list -t all
NAME USED AVAIL REFER MOUNTPOINT zstorage 5.19T 1.48T 5.19T /zstorage
kevin@atlas:~$ sudo zpool status -v
pool: zstorage state: ONLINE scan: scrub in progress since Sat Apr 5 10:49:13 2014 317G scanned out of 7.79T at 262M/s, 8h18m to go 1.50M repaired, 3.97% done config: NAME STATE READ WRITE CKSUM zstorage ONLINE 0 0 0 raidz1-0 ONLINE 0 0 0 ata-WDC_WD30EZRX-00DC0B0_WD-WCC1T1735698 ONLINE 0 0 0 (repairing) ata-WDC_WD30EZRX-00DC0B0_WD-WMC1T0506289 ONLINE 0 0 0 ata-WDC_WD30EZRX-00MMMB0_WD-WCAWZ2711600 ONLINE 0 0 0 raidz1-1 ONLINE 0 0 0 ata-WDC_WD15EADS-00P8B0_WD-WMAVU0454800 ONLINE 0 0 0 ata-WDC_WD15EADS-00P8B0_WD-WMAVU0524642 ONLINE 0 0 0 errors: No known data errors
kevin@atlas:~$ df -h /zstorage/
Filesystem Size Used Avail Use% Mounted on zstorage 6.7T 5.2T 1.5T 78% /zstorage