Extend Pool or Create New??

Kuro Houou

Contributor
Joined
Jun 17, 2014
Messages
193
Hi, today I have a 12 bay supermicro FreeNAS server, its been running for 3 great years with 6x8TB drives in a RAIDZ2 setup for a total of about 28TB of usable space. I have since gone over the 80% recommended storage utilization (I have 4.27TiB free now) and have purchased 6x14TB drives which in a RAIDZ2 setup should give ~50TB of usable space.

My question is, can I expand my existing Pool or because the drive sizes are different I should just create a new pool?

If I go into the console and walk through the Extend option (being careful not to accept that yet), adding my 6 drives, it says the following,

1596763744625.png


"Raid-z2
Estimated raw capacity: 50.93 TiB "

"Estimated data capacity available after extension.: 59.55 TiB " Am I missing something, is it not going to give me the full 50TB of usable disk space for the 6x14TB drives? I would have thought it would say something like 78TiB here.

Just curious what is going on here, is the extend option only good if you use the same size disks? If so, is my only option to create a new pool?

Third option might be to just scrap the idea of having 12 drives in this system and rebuilding the existing array one by one replacing the old drives with the 14TB drives, essentially just going from 28TB on this server to 50TB.... I have a backup FreeNAS box I could put the other drives in which actually might make more sense as it won't have enough space to provide a backup for 78TB lol... I'll think about this option more.. ignore this thought, back to the question at hand.. to extend or create a new pool :)

Thanks
 
Last edited:

Heracles

Wizard
Joined
Feb 2, 2018
Messages
1,401
is it not going to give me the full 50TB of usable disk space for the 6x14TB drives? I would have thought it would say something like 78TiB here.

RaidZ2 will take 2 drives for redundancy, so you end up with 4 drives of usable space. That is why it will not add 6x 14 = 84TB.

And you are doing it right : you are adding a new vDev with the same architecture as the first one. Both will be 6 drives RaidZ2 vDev.

Better to extend the pool instead of having 2 separate. The only reason for 2 pools is whem you need different pool-level options.

So the way you described it, you are good to go.
 

Kuro Houou

Contributor
Joined
Jun 17, 2014
Messages
193
I understand RaidZ2 will take 2 drives, I guess my worry is why it says estimated data capacity is 59.55TiB. by my estimation a RaidZ2 with 6x14TB drives is ~50TiB by itself, but with the existing pool that is 28TiB the total capacity should be 78TiB right? My worry is I'd only have 59.55TiB of total capacity of I did this.
 

Kuro Houou

Contributor
Joined
Jun 17, 2014
Messages
193
So still curious about the original question I had and why it said my total capacity would only be 59.55TiB.. but with that said, I have decided to just replace my drives that are in the system today and upgrade them to the 14TB drives, effectively increasing capacity from 28TB to 50TB. I will be following the directions from the user guide, section 8.1.11 to replace each disk 1 by 1. Luckily I can fill my server with all the disks so no need to power down the server while doing all this :)
 

artlessknave

Wizard
Joined
Oct 29, 2016
Messages
1,506
hmm. that's odd. i'm trying to replicate in a VM.
I would guess that the estimate is based on the existing drives (24+24) instead of using the new drives size (24+56), which seems bug-like
 

artlessknave

Wizard
Joined
Oct 29, 2016
Messages
1,506
nope, the VM disks (6gb+12gb) show the expected space (starts out ~15GB, adds ~50gb, shows a total of ~60GB), so idk how you got that screenshot.
its probably just a display error, and you could probably just continue...but if you wanna be slightly paranoid replacing should work fine. make sure your autoexpand is set right though.
you don't seem to have the freenas version listed.
 

Kuro Houou

Contributor
Joined
Jun 17, 2014
Messages
193
Yeah, guess I won't know if its a display bug or not, since I have started replacing the first drive now (resilvering as I type). I am on, FreeNAS-11.3-U3.1. Where would the autoexpand option be located? Want to make sure I have that set right.

update.. found the command,

root@freenas:~ # zpool get autoexpand v01
NAME PROPERTY VALUE SOURCE
v01 autoexpand on local


Looks like I am good to go from what I can tell.
 

artlessknave

Wizard
Joined
Oct 29, 2016
Messages
1,506
yup should be
(it can be turned on afterward too, but requires an extra step to get it actually expand)
one you replace everything, you could try expanding with the old drives again and see if it shows the size more correctly. or you could just leave it since its already nearly double.
 

Kuro Houou

Contributor
Joined
Jun 17, 2014
Messages
193
Just a quick update, about a week later all disks finished being replaced (6 disks in total). Now about 50TB available :) Now I have to swap my backup NAS with the disks that just came out of this NAS
 
Top