can more disks be added to Z2 ?

[AndroGen]

Sorry for asking a questions, which might have been touched already - I could not find an answer, that would eliminate the uncertainty.

the case:
Z2 is created using e.g. 6 HDDs.
Then 2 additional HDDs are purchased.
Can existing Z2 array be expanded by adding 2 new HDDs, or it needs to be rebuilt completely using not 6, but 8 HDDs.

My understanding is: it needs to be rebuilt, and it is not possible to add additional discs to it, but I am not sure...

Could you please help to clarify this uncertainty in my understanding?
Thanks

 

[Basil Hendroff]

If your vdev consists of six disks, then you cannot expand the vdev without rebuilding it. However, you can expand a pool by adding a second vdev, which include the 2 disks (mirrored for redundancy). To understand your choices, I suggest you review https://forums.freenas.org/index.ph...ning-vdev-zpool-zil-and-l2arc-for-noobs.7775/.

 

[AndroGen]

Thanks @Seymour Butt, this sounds like I have learned it correctly.
Thanks for redirecting me to this great PPT - I have studied it
I just was not sure, whether I have understood it correctly, hence wanted to check.
Expansion by adding two disks in mirror vdev would mean loosing one disk space - this sounds like it is better to have right number of discs right form the beginning.

 

[Jailer]

this sounds like it is better to have right number of discs right form the beginning.

Correct and that's why it pays to really sit down and figure out what your storage needs are going to be not just now but in the near future as well.

 

[danb35]

this sounds like it is better to have right number of discs right form the beginning.

Correct. There's work ongoing that would change this (expected with FreeNAS 12 at this point), but as it currently stands, the advice you've been given is correct.

 

[AndroGen]

Thanks for the confirmation!

that's why it pays to really sit down and figure out what your storage needs are going to be not just now but in the near future as well.

That's why I am asking.
Consolidating big volume means it becomes much more difficult to move it back and forth for the rebuild prospective.