[DRBD-user] linstor-proxmox-2.9.0

[Yannis Milios]

Sorry for interrupting, but I wanted to share my experience with this as
well (see below) ...


> What do you mean by that? The DRBD resource (== storage for the
> controller VM) is brought up by the drbd.service and can then be
> auto-promoted. The plugin code ignores that VM. The Proxmox HA service
> should do its job and start the VM on one node. So again, where exactly
> does that chain break in your setup?
>

In my case, I had success in making the LINSTOR controller HA in two
different clusters, but by following a slightly different approach.

In documentation, it's stated the following ...

"The basic idea is to execute the LINSTOR controller within a VM that is
controlled by Proxmox and
its HA features, where the storage resides on DRBD managed by LINSTOR
itself."

So by this, I understand that the LINSTOR controller VM will be managed by
PVE by using its HA feature, all good so far.
Then it's stated that, the storage that will be used to store this VM will
be DRBD, which will be managed by LINSTOR itself.


 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Question: Isn't the above a paradox? How can PVE HA start a machine which
is stored in a shared storage, which the only way to make it available, is
by starting this HA VM  in the first place?

My tests showed that whenever PVE tried to start this HA VM, it failed,
because the underlying storage (DRBD) was not available  (and yes,
drbd.service was set to "enabled" and was "started" in all nodes).
Checked inside /var/lib/linstor.d to see if the resource file for this VM
was in there, but it wasn't. Actually, there were no resource files at all
in there, apart from "linstor_common.conf".

Question: Where should drbd.service find the resource configuration file
for the LINSTOR controller VM? Inside /var/lib/linstor.d or in /etc/drbd.d ?

For the former, LINSTOR should auto generate that resource file, but it
doesn't, because the controller is not available (yet) ?. For the latter,
someone can manually create a .res file (the classic DRBD approach), copy
it to all nodes and do the required backed storage preparations before
deploying the LINSTOR controller VM.

I used the latter method and so far seems to work properly (manually
created .res files in /etc/drbd.d). As, Proxmox supports multiple storage
types, storing LINSTOR controller VM in a NFS storage for example, should
be an alternative, easier to setup option.
Almost all Proxmox cluster setups, have some type of NFS server (for
storing ISOs,templates etc) anyways, but I understand that Linbit want to
offer a purely DRBD solution, without the need to use 3rd party stuff.

No matter which option you'll choose, as soon as the LINSTOR controller HA
VM is up and running, all the rest should run properly without issues.

Yannis
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