Short Question: Replacement and Upgrading Mirror Pool

[MjSmith]

Hi Guys,

to keep it short: I have to replace a Mirror Pool and want also to decrease it.

After reading into it i made the choice to choose a 2-Mirror Setting.
First i was at a ZRaid1 - then ZRaid2 but the benefit of expanding easily a Mirror Pool by adding another pair of disks sounds like the best solution.

That being said i installed the 4 new disks.

Question now: Is it a good solution to just add the new disks as VDevs to the existing Data Pool and wait for resilvering and then remove the two disks i want to replace or should i start with a new Pool instead and use the replication tasks to copy the Data?

Thanks for reply!

 

[Etorix]

If you current pool consist of mirrors only, add new vdevs with the new disks. There is no resilver: You indicate through the GUI that you want to remove a vdev and then you wait for ZFS to migrate the data.

If the pool has any flavour of raidz in there, you must create a new pool and replicate your data to it. Raidz# = no removal.

 

[MjSmith]

Thx!

No the current Pool is also a 2 Disk Mirror, so i just would add two more 2 Disks mirrors and the plan is then to remove the two first Mirror.

So my idea is practical and should work fine without dataloss right?

 

[NugentS]

Correct

 

[Davvo]

Only if each of the two new drives has enough space to store the data already on the pool.

 

[MjSmith]

Guys it seems it isnt that easy :).

When i remove the old mirror i got an error which says the disks are busy. Well my apps are loaded from that pool.
But as you mentioned the data should copied on the other mirrors in the removing process which i dont see at all.

What do i miss?

@Davvo they are all 4TB. So i doubled the size of the pool at the same time. No space issues to expect :).

 

[Davvo]

When i remove the old mirror i got an error which says the disks are busy. Well my apps are loaded from that pool.
But as you mentioned the data should copied on the other mirrors in the removing process which i dont see at all.

What do i miss?

IIRC you have to stop all your apps before doing this.

 

[MjSmith]

But then they really copy the data to the other disks?

I mean you said it but im very scared because truenas doesnt have any note or information neither in the operation itself nor on there article for vdevs operations ... thats not very ... user friendly.

 

[NugentS]

It should do - that the way removing a mirror works - ZFS just transfers the data over in the background. I have done it, it works

 

[MjSmith]

Well it worked but doesnt solved my problem why i started the replacement ... new thread for that ...