XigmaNAS

Hi all, I am a complete noob when it comes to ZFS, but have been having some fun with it. I have an existing pool made up of two mirror vdevs. Each mirror is made up of 2, 1 TB drives.

I just happened to have a 1.5 TB and 1.0 TB drive laying around and thought I could create another mirror vdev and just sacrifice the 500 MB of the 1.5 TB drive. I was able to create the vdev successfully, but I get an error when attempting to add the vdev to the pool.

vdev add...
invalid vdev specification
use '-f' to override the following errors:
mirror contains devices of different sizes

Ok, so they are different sizes, great. Can ZFS still use the mirror and get the performance I'd like? I don't care about the .5 of the 1.5 TB drive. I just want to add another vdev mirror to the pool to further increase IOPS.

I would jump into the cli and just run the command manually with the -f, but I am not sure what the full command looks like. Can someone clue me in?

Wow, it took me absolutely forever to figure this out.... Painful learning new things. Here are the commands and output I used from an SSH session. I hope it is still getting the performance benefit and is not trying to make use of the 500GB some wacky way.


nas4free: ~ # zpool list
NAME SIZE ALLOC FREE FRAG EXPANDSZ CAP DEDUP HEALTH ALTROOT
zPool_01 1.81T 308G 1.51T 8% - 16% 1.00x ONLINE -


nas4free: ~ # zpool status
pool: zPool_01
state: ONLINE
scan: none requested
config:

NAME STATE READ WRITE CKSUM
zPool_01 ONLINE 0 0 0
mirror-0 ONLINE 0 0 0
ada0 ONLINE 0 0 0
ada1 ONLINE 0 0 0
mirror-1 ONLINE 0 0 0
ada3 ONLINE 0 0 0
ada4 ONLINE 0 0 0

errors: No known data errors

******************** The "-n" is really handy.. It seems to test the change without actually making it and tells you what will happen. Here is me re-creating the error:
********************
nas4free: ~ # zpool add -n zPool_01 mirror ada2 ada5
invalid vdev specification
use '-f' to override the following errors:
mirror contains devices of different sizes

******************** And again using the "-f" option.. Still have the "-n" there to see what might happen without making the change. notice the command output says "would update" Pretty neat...
********************
nas4free: ~ # zpool add -n -f zPool_01 mirror ada2 ada5
would update 'zPool_01' to the following configuration:
zPool_01
mirror
ada0
ada1
mirror
ada3
ada4
mirror
ada2
ada5

******************** And finally making the change... Wow, that took a while to figure out.
********************
nas4free: ~ # zpool add -f zPool_01 mirror ada2 ada5
nas4free: ~ # zpool status
pool: zPool_01
state: ONLINE
scan: none requested
config:

NAME STATE READ WRITE CKSUM
zPool_01 ONLINE 0 0 0
mirror-0 ONLINE 0 0 0
ada0 ONLINE 0 0 0
ada1 ONLINE 0 0 0
mirror-1 ONLINE 0 0 0
ada3 ONLINE 0 0 0
ada4 ONLINE 0 0 0
mirror-2 ONLINE 0 0 0
ada2 ONLINE 0 0 0
ada5 ONLINE 0 0 0

errors: No known data errors
nas4free: ~ #

actyler1001 wrote:vdev add...
invalid vdev specification
use '-f' to override the following errors:
mirror contains devices of different sizes

Ok, so they are different sizes, great. Can ZFS still use the mirror and get the performance I'd like? I don't care about the .5 of the 1.5 TB drive. I just want to add another vdev mirror to the pool to further increase IOPS.

I would jump into the cli and just run the command manually with the -f, but I am not sure what the full command looks like. Can someone clue me in?

-f is used second time you try to apply a config, YES is not intuitive, but works.

eg: you push apply buton first time in webGUI and have the error that you say, then apply second time same button , this time use -f option and works.

Perhaps is not well docummented but is it.

Huh? I didn't see an option to hit the button a second time. There was only a back button on failure..... I tried it multiple times before going to the CLI.