Create Pool

[Yaniv]

Hello,
I currently have 2 HDDs (WD Red Plus 4tb model WD40EFPX) and I want to but a 3rd one,
I didn't start any configuration with proxmox for this 2 but I am willing to buy a 3rd one
(originly I bought 3 from amazon but one arrived damaged and not working)

before I start working with proxmox I want to know what is the best way to configure a zfs pool from this 2 HDDs that in the future I would be able to add a 3rd one and even a 4th one if I would like to (and so on)
the goal is to make a VM for homeassistant and another VM for debian that will have dockers installed in it such as Jellyfin, nextcloud and more but all will use the same pool.

I would be glad to learn from you experince and wisdom.
A friend suggested making a TrueNAS VM and configure everything from there-the ZDS and the dockers("apps") , what is your opinion?

 

[Kingneutron]

Start with a 2-drive ZFS mirror pool and add +2x more drives at a time (of equal or larger size) to expand the free space. This should give you a "RAID10 equivalent"

Adding only a 3rd drive is no bueno, as without a matching mirror it would be a single point of failure.
Make sure you set ' autoexpand=on ' before adding another "column" of mirror disks.

 

[Yaniv]

Start with a 2-drive ZFS mirror pool and add +2x more drives at a time (of equal or larger size) to expand the free space. This should give you a "RAID10 equivalent"

Adding only a 3rd drive is no bueno, as without a matching mirror it would be a single point of failure.
Make sure you set ' autoexpand=on ' before adding another "column" of mirror disks.

Thank you for the answer, I have another question for something I am trying to understand,

lets say I create a pool of 3 drives*4TB, if I understand correctly the amount of space I will have is 8TB and not 12TB, what happens if one of the drives failes? all the data is saved? and if I want to replace it with a new one is it possible or do I have to backup everything and create a new pool? I'm a bit confused

 

[peter247]

Thank you for the answer, I have another question for something I am trying to understand,

lets say I create a pool of 3 drives*4TB, if I understand correctly the amount of space I will have is 8TB and not 12TB, what happens if one of the drives failes? all the data is saved? and if I want to replace it with a new one is it possible or do I have to backup everything and create a new pool? I'm a bit confused

Yes , 3 disks equals 2 disks of data and 1 disk for parity ( but more like 7.7tb ), so if anyone disk fails you can regenerate the failed disk , BUT if a second disk dies while you are regenerating your data, all is lost . SO YES IF ONLY 1 DISK ( raidx1).
If a disk dies , you need to replace the dead disk and make it resilver , BUT a don't think this is automatic you need to use the console and use
zpool replace pool_name drives_name etc
OOOPs I didn't fully read your first post , no you can't turn a 2 drive mirror into a 3 drive raidx1 without backing up and starting again .

 

[Yaniv]

Yes , 3 disks equals 2 disks of data and 1 disk for parity ( but more like 7.7tb ), so if anyone disk fails you can regenerate the failed disk , BUT if a second disk dies while you are regenerating your data, all is lost . SO YES IF ONLY 1 DISK .
If a disk dies , you need to replace the dead disk and make it resilver , BUT a don't think this is automatic you need to use the console and use
zpool replace pool_name drives_name etc

Thanks both for the detailed answers!

 

[peter247]

Thanks both for the detailed answers!

oops I didn't fully read your first post , my post as been edited a little , sound like you have a mirror and want to add a extra disk , which is a , NO NO , because adding a extra disk will make it a mirror and a single disk strip , so a single disk and you will loose all your data .
you need to back up the 2 disk mirror and make a 3 disk raidx1 instead .