ZFS over iSCSI and DRBD

[AYP]

I've been given the task of installing Proxmox VE on existing iron: 3 "computing" nodes with relatively few discs and 2 "storage" nodes with plenty of space.
My idea is to use the 3 nodes for running VMs and use ZFS over iSCSI with DRBD to have a semblance of HA, I've come to this conclusion after quite a bit of reading and asking around.
I'm not new to Proxmox (in very basic setups) but this is a lot of stuff to take in, hence I'm asking here for opinions from more experienced users. My focus is reliability and I plan to later setup a Proxmox backup server.

As I understand I would create identical zvols on storage1 and storage2, configure DRBD to keep them synchronized, then define on each storage node an iSCSI target on top of the DRBD device. Am I right up to this point?

From here things get a bit more fuzzy. How do I instruct the 3 "computing" nodes to use the two iSCSI targets as one so that there is a switch between them in case of failure? I understand that "multipath" may be the key word here but I've not found a definitive answer.

Thanks for your help!

 

[bbgeek17]

As I understand I would create identical zvols on storage1 and storage2, configure DRBD to keep them synchronized, then define on each storage node an iSCSI target on top of the DRBD device. Am I right up to this point?

From here things get a bit more fuzzy. How do I instruct the 3 "computing" nodes to use the two iSCSI targets as one so that there is a switch between them in case of failure? I understand that "multipath" may be the key word here but I've not found a definitive answer.

Hi @AYP , welcome to the forum.

There is a lot to "unpack" here. Much more than I can type at this time of the morning on Thursday.
The short version: it does not work this way, at all. Two independent iSCSI daemons do not make multipath. Synchronizing ZFS at the lower storage level will cause data corruption. Etc.

Sometimes no HA is better than "semblance" of HA.

Best of luck in your research.

---

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

 

[AYP]

Well, thank you very much for putting me on a better track!
Back to research now.

 

[floh8]

Synchronizing ZFS at the lower storage level will cause data corruption. Etc.

could u explain this in detail?

Am I right up to this point?

yes, u are

But: zfs-over-iscsi is an access solution for a single storage. It seems that u wanna build a dual storage with HA. U find the right doku on the linbit site: https://linbit.com/solutions-and-how-to-documentation/