iSCSI+lvm snapshots not allowed

[LuisManson]

Hello, I have managed to connect an iSCSI volume with LVM but jsut found snapshots are not allowed on this backend.
Is there a way to achieve this? Storage is a QNAP so i guess i can not use ZFS on top of it...

 

[bbgeek17]

You can use LVM _thin_ on iSCSI disk and get LVM snapshots , but storage cannot be shared. I.e. each LUN is used only on one node.
You can use LVM thin on iSCSI as shared storage, but will not have snapshots.
You can take snapshots on the storage side, but they will not have VM state. So good for "data" disks" in coordination with your app.
You can implement, on your own, a clustered filesystem that supports snapshots.

The table here https://pve.proxmox.com/wiki/Storage tells you what combinations are officially supported out of the box.

QNAP is not one of the storages that can just work with ZFSoverISCSI technology. You can write you own plugin to do so.

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Blockbridge: Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

 

[LuisManson]

Thanks for the quick reply! i'll move to thin pool then.

just for completeness I've discovered qnap uses ext4 and there are some products which can use ZFS using another qnap OS

 

[bbgeek17]

Just because its using ZFS doesnt mean it will be compatible with "zfs" backend implementation in Proxmox.

From "man pvesm":

ZFS OVER ISCSI BACKEND
       Storage pool type: zfs

       This backend accesses a remote machine having a ZFS pool as storage and an iSCSI target implementation via ssh. For each guest disk it creates a ZVOL and, exports it as iSCSI LUN. This LUN is used by Proxmox VE for the
       guest disk.

       The following iSCSI target implementations are supported:

       •   LIO (Linux)

       •   IET (Linux)

       •   ISTGT (FreeBSD)

       •   Comstar (Solaris)

           Note
           This plugin needs a ZFS capable remote storage appliance, you cannot use it to create a ZFS Pool on a regular Storage Appliance/SAN

I dont know how Qnap implements their iscsi, but there is a good chance they made proprietary changes to both iSCSI and ZFS management.
https://forum.proxmox.com/threads/zfs-iscsi-from-qnap-nas.47586/

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Blockbridge: Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox