Expanding striped mirror array (4disks)

blckhm

Dabbler
Joined
Sep 24, 2018
Messages
42
Hi,

I just wanted to ensure that, how many drives should I need to expanding my pool?

My setup is 4x 12TB disks which separated 2x Mirrored like below.

Should I make another 2x 12TB mirrored vdev and attach that into the pool such as mirror-3.

1586009656979.png


Thanks
 

sretalla

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Jan 1, 2016
Messages
9,702
Should I make another 2x 12TB mirrored vdev and attach that into the pool such as mirror-3.
Yes.
That seems perfectly reasonable.
 

blckhm

Dabbler
Joined
Sep 24, 2018
Messages
42
So I am wondering what happens after expanding.

For ex. we want to write 6kb data, it should be striped by 3kb’s per vdevs. And read ops. obtained from 2 vdevs concurrently.

after expanding process, new data should be striped by 2 kb for 3 vdevs but what happens to older ones?

Is there any rebalancing process after expanding?

If no, my older data reading speed stucked to 2x and fresh written’s should 3x ?
 

JaimieV

Guru
Joined
Oct 12, 2012
Messages
742
There's no rebalancing built into the system, you'd have to duplicate data or move it off and back on yourself to get it to spread around.

If you have a bunch of media files, don't bother with rebalancing them - no point. If you have some stuff that you'd like to be quicker, do the manual task. If you have VMs or iSCSI using block devices you'd have to do those by replicating away and back.
 
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