Ephemeral storage in HA environment

[atbakken]

I have a couple guests that I would like to make highly available. These guests have some sort of ephemeral cache storage for things like downloading or transcoding that I would prefer to store on the hosts local disk. The information in that directory is not important to keep, and I don't want to waste resources transferring or duplicating it to a shared storage.

However, I am not able to make these guests truly highly available due to having that local storage. If all hosts are up it can migrate the local storage correctly, however if the host is lost abruptly the guest is not able to start on another host without that original local disk being available.

I am curious to see if there is a feature that I'm missing that can handle this configuration or if others have the same issue and maybe found a workaround.

 

[abader]

You could try to move your important Data to the Shared Storage and replicate the unimportant disk between the Hosts via zfs replica

you should disable Replikation flag in your shared storage disk

Never tried this before. Good Luck

 

[zrav]

I have a similar scenario/requirement. We use VMs and CTs that have both shared (persistent) storage and temporary (fast) local storage. We don't want to copy the temp data when migrating or failing over to another node.
Ideally we'd have the option to mark a VM disk or CT mount point as ephemeral, meaning that when the VM/CT is migrated or fails over, the temp disk is just recreated on the new host.

 

[VictorSTS]

An option could be to use hookscripts [1] to recreate the "ephemeral" disk every time the VM starts. Somewhat risky and the OS / Apps would have to create the filesystem directory tree every time. You could also create a local drive on every host, put a filesystem, etc so when the VM boots it finds such local disk. A bit too clumsy for my taste...

Other option could be to setup a couple of VMs as NFS servers with application level HA (a keepalived should be enough) and mount the ephemeral drive from it.

[1] https://pve.proxmox.com/pve-docs/pve-admin-guide.html#_hookscripts