LVM striping: a good idea?

[janvv]

I have grouped similar disks into LVs. NVMe SSDs together in one LV, the SATA SSD's together the second LV, and a bunch of spinning disk together in one big LV.

My main concern about this is (if I understood it correctly): the system first fills up the first physical disk before using the next one in the group.
If that is true, then the last disk is sitting in the system, waiting for the other disks to fill up, before any byte is written to it.
To improve this I can change the LVs to use striping. This will even improve the disk IO speed. One caveat: ideally the disks should be of the same size.

Another question is: what happens to the volumes created by Proxmox for the VM disk images? Will they benefit from the striping of the underlying volume, or not?

 

[shanreich]

I would be a bit careful with this. If one disk fails, then ALL of the data/disks stored in the striped LV will be lost. The other way around, if all your disks are full, only 1/n of all the data/disks will be missing in the case of a single disk failure. This reduces the effort of recovering in the case of a drive failure and only the VMs located on this specific disk will be affected compared to all the VMs being affected.

This is the main reason why RAID 0 is strongly discouraged. Anyway, you should have backups of the disks anyway if they are important.

If this downside is acceptable for you, then there should be no issue I am aware of with using striped LVs. Proxmox disk images should benefit from the increased speed.

If you are looking for a more flexible/powerful storage solution maybe looking into ZFS might be worth for you?

 

[janvv]

I think ZFS is too much overhead for a homelab. In case of failure, I have Ansible playbooks to re-create the containers and VMs that are vital for my home network. And what is 'vital'... my home won't get unlivable when PiHole or Plex don't work. (My wife might disagree though ) In the worst case I use my phone's hotspot.

I am making backups. ZFS comes with additional disk space costs, and it will use lots of my RAM.