Extending a pool with mirrored drives

I have 2 different pools with 2x8tb and 2x 12tb harddisks. I want to add 2x12 tb to extend the second pool. What i would like to know is, if i add a second mirror to 2x12 tb pool do they work like a stripe speedwise? or should i backup and remake the vdevs with 4 harddisks like raid 10 in a new pool?
Thanks in advance.


You should have backups to begin with, raid is not a backup :wink:

Depending on your use case you may want to look into a rebalancing script, because the data is not automatically rebalanced (i.e. striped across both vdevs).

edit: fixed “typo”

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Thanks for the quick reply chuck, where can i find a rebalancing script? any advice?

:warning: Understand that using any rebalancing script will make your existing snapshots moot.

So you will either have to destroy your currently existing snapshots, or keep them and deal with the wasted space that is "2 x stored data"

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Thanks for the script, I dont have any snapshots i am counting on mirror eventhough i know it is not a backup :grin:

“Siri. Set a reminder for three years from today to see if @Faruk_Durusoy still has his data.”


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I am using enterprise grade hdds; seagate exos and wd red pro series, i see it very low chance to lose 2 disks at the same time at the same pool, it never happened before in my 25 years computer life :smiley: :smile:

“Siri. Set a reminder for four years from today to see if @Faruk_Durusoy still has his data.”


There’s two types of people: those who have backups and those who will have backups :wink:


Hi winnie, i tried rebalancing script and after creating a file with .balance extension it fails giving operation not permitted error although i am logging web panel as root, what may be the reason? i tried playing with acl and also permissions from windows too but nothing worked. is there any other way? :frowning: