Add a disk to RAID-Z pool

[martijnanne]

Hi,

I'm still not very sure how this works, after reading some hours I would like to have some people confirm my thoughts.
I have FreeNAS-8.2.0-RELEASE-p1-x64 (r11950) running with the FreeNAS OS on a 60GB SSD drive and one RaidZ config with 3 2TB disks in one volume called Set1. Now I would like to expand that volume called Set1 by adding one 1TB disk, can I just use the volume manager for this to add the disk to the existing volume and increase the total available storage of Set1?



thanks in advance for answering!

 

[ben]

You can stripe it in, but it will not be included in the parity of the RAID-Z pool, and instead will be a permanent single point of failure for the combined pool. This is strongly recommended against. If you must add a small number of disks at a time, add two at a time in mirrors. The best case is always to build your pool to its final capacity right out of the gate.

 

[jgreco]

No. Well, yes, but then you won't have any protection for that 1TB, so effectively "yes but very stupid--don't do that."

A ZFS pool is made out of vdevs and ZFS doesn't care too much how cleverly or how stupidly you make your vdevs, or that they match, etc.

With the RAIDZ vdev, you have data protection against loss of any one of those disks in that vdev. You cannot easily change that vdev (though you can in theory swap each drive out, one at a time, for 3TB drives and let it rebuild, but this is just a bit dangerous and not for beginners). You can add a new vdev. A mirrored pair of 1TB is one option that would give you data protection. A RAIDZ of three 1TB's would give you more space and data protection too. But if you add a vdev without data protection, you're pretty much guaranteeing trouble if you lose that 1TB drive.

 

[Hubby72]

Hello,

to pick this topic up - i excactly have done this due to a online guide i found which uses that as an example how to expand a volume. Afterwards i read the notice in this guide and verified my newly setup chaos.
No i want to get rid of this.
I now have a raidz with 4 disks and the new disk is added as a stripe to that.
i already tried to take the single disk offline or to detach - without success. (no valid replicas)
Also did a scrub and tried it again.

Any way to get this disk back out of this - for sure without loosing data :) ?

 

[cyberjock]

I specifically discuss your exact scenario in the ZFS guide I wrote. I put a link in my sig so make sure to check it out.

 

[Hubby72]

Oh Ok! Thanks.

What a shame that i did not find your guide before finding the other HowTo Guide - in that moment i was adding the disk i knew i did something stupid :) But it was all so easily to do this that i thought ZFS will stop me before..but yes you're right.
Good Guide btw.

Then i will stay with it to copy around my data anand then reconstruct a new pool with full size at least.

 

[cyberjock]

The real problem is that with Windows it generally will give you very clear cut "if you do this you can't undo this" type of stuff. With FreeBSD the system does give some warnings, but for the most part its on the admin to not do something stupid. FreeBSD is far more powerful feature-wise than Windows. It is not possible to have warnings for everything because there are so many possible configurations that some things you do won't matter at all and others can have catastrophic consequences. It's a very steep learning curve for anyone that's lived on Windows for decades and is suddenly jumping in the FreeBSD pool. I jumped in only after I did a boatload of reading and several weeks of experimenting with a VM.

 

[MutoSan]

Hey Cyberjock. Can it be that your link for the guide in the signature is wrong?