How to change size of a mirror set in a RAID 10 array?

[Edu@rd]

Hello folks,
I have 6 WD RED 3TB and 2 Seagate Barracuda 4TB in my array at the moment.
I'd like to create 4 mirror sets (RAID10) but with the same capacity.
I don't care loosing 2TB, since I'm going to replace them with 3TB REDs soon.
If I create a mirror set with the 2 Barracudas of course is used the entire disk capacity.
Is it possible to shrink or customize the size before creating the ZFS volume? I didn't find any option in the FreeNAS gui.
Thanks in advance.
;)

 

[anodos]

Your pool as it is will be striped across 3 x 3TB mirrored vdevs and 1 x 4TB mirrored vdev. You're not really losing any capacity. You're thinking about RAIDZ vdevs.

 

[Edu@rd]

Thanks for the quick reply, actually I do want loose capacity because I'm going to replace the two 4TB drives with 3TB drives. :P

 

[anodos]

Thanks for the quick reply, actually I do want loose capacity because I'm going to replace the two 4TB drives with 3TB drives. :p

Yeah, reading comprehension fail. Kids kept waking up last night. :)

 

[Edu@rd]

Yeah, reading comprehension fail. Kids kept waking up last night. :)

Eheh, no problem man, I perfectly understand. Thank you anyways :)

 

[cyberjock]

I don't even know what the heck you are trying to say. 4 mirrored sets? Ok, so you have 8 drives that are going to be 4 mirrored vdevs. What size disks? You didn't specify.

This thread seems to be written by someone that was partially asleep. ;)

Can you elaborate a little more on where you are and where you are trying to go?

 

[Edu@rd]

I don't even know what the heck you are trying to say. 4 mirrored sets? Ok, so you have 8 drives that are going to be 4 mirrored vdevs. What size disks? You didn't specify.

This thread seems to be written by someone that was partially asleep. ;)

Can you elaborate a little more on where you are and where you are trying to go?

Hi, if you read again the first post I think I mentioned everything.
Btw I have 6x RED 3TB and 2x Barracuda 4TB.
Maybe I didn't explain my problem very clearly, sorry about that.
I'll try again with the help of this picture:

As you can see I have 4 mirrored sets or vdevs.
I'd like to customize the capacity of the first vdev that I pointed out in red.
I need to match the capacity of the first vdev to the others since I'm going to replace the two "temporary" 4TB drives to the smaller REDs 3TB.
If I create the pool right now as showed in the picture, I'm stuck with the two 4TB drives and I can't replace them with smaller ones.

 

[cyberjock]

Ah. Ok. There wasn't enough information to validate that those 8 drives are the exact 8 drives you were using. And your question seems to imply you understand the limits with vdevs, but I don't understand how you don't know how to deal with the situation.

In short, you cannot downsize a vdev after it's been created. PERIOD. You obviously know this.

That being said, what you need to do is create two vdevs that have a 4TB and 3TB mirrored. That will force the vdevs to 3TB. Later you can rearrange the 4TB to be in the same mirror to get your 4TB mirror back to full capacity. You will likely not be able to do this with the current volume manager. So you'll need to click the manual manager and create the vdevs yourself. Once done you'll be able to do what you want. ;)

 

[Edu@rd]

Ah. Ok. There wasn't enough information to validate that those 8 drives are the exact 8 drives you were using. And your question seems to imply you understand the limits with vdevs, but I don't understand how you don't know how to deal with the situation.

In short, you cannot downsize a vdev after it's been created. PERIOD. You obviously know this.

That being said, what you need to do is create two vdevs that have a 4TB and 3TB mirrored. That will force the vdevs to 3TB. Later you can rearrange the 4TB to be in the same mirror to get your 4TB mirror back to full capacity. You will likely not be able to do this with the current volume manager. So you'll need to click the manual manager and create the vdevs yourself. Once done you'll be able to do what you want. ;)

Thanks for your reply :)
Sure I know I can't downsize a vdev and that's why I was asking if was possible to change capacity before creating it.
So only way to force a vdev be 3TB is to mix the drives of course.
Actually I knew that was the best way to do that but not the only. I was hoping to find a different approach (I'm not a ZFS expert) but yes in the end the final result would be the same.
Thanks again. :)

PS:Thanks for suggesting me the manual manager (I'm not used to the FreeNAS gui, I'm a napp-it user!)

 

[cyberjock]

There are alternatives. Like if you were doing FreeBSD you'd simply create a 3TB partition and use that. But since FreeNAS is an appliance it makes lots and lots of decisions for you.

4k block size? Yes please.
4k alignment? Yes please.
Use the entire disk? Yes please.
Use whole disks or partitions? Partitions
Create a swap partition? Yes please.

Believe it or not, you've lost a great deal of options by going with FreeNAS. BUT, most of those options that are taken away are options that 99% of forum users would set on their own if they were a FreeBSD and ZFS expert. Nobody would question doing 4k sectors and such. That just make sense. ;)

 

[Edu@rd]

Yes I see...I installed FreeNAS 2 days ago and as you said the first thing I realized is how poor it is compared to napp-it (I found it amazing as ZFS appliance). Also managing the pools is kinda bad and tons of stuff are missing.
Of course avoiding appliances is the best way to get as much control possible, but honestly I don't have time to learn all these stuff and napp-it + basic solaris commands covers perfectly all my needs.
I decided to go with it just because was easier to setup and because I'm not going to do anything fancy with this build, except a Plex media server.

 

[Edu@rd]

There are alternatives. Like if you were doing FreeBSD you'd simply create a 3TB partition and use that. But since FreeNAS is an appliance it makes lots and lots of decisions for you.

4k block size? Yes please.
4k alignment? Yes please.
Use the entire disk? Yes please.
Use whole disks or partitions? Partitions
Create a swap partition? Yes please.

Believe it or not, you've lost a great deal of options by going with FreeNAS. BUT, most of those options that are taken away are options that 99% of forum users would set on their own if they were a FreeBSD and ZFS expert. Nobody would question doing 4k sectors and such. That just make sense. ;)

Hey cyber sorry to bug you again but I got a quick question.

How FreeNAS handles filesystems?
As far as I understood seems that is taking care of creating them automatically after you create the volume/pool.
But what if you extend a volume like in my case with mirrored vdevs?
Usually I create my pool as I wish and the last thing I do is to create the filesystems (as it should be).
I'm a bit lost here...
Thanks :)

 

[cyberjock]

That's the only way. Zpool is your base storage and you build datasets as necessary. I'm not sure what your question is.