[DRBD-user] linstor-proxmox-2.9.0

[Roberto Resoli]

Il 27/08/2018 10:53, Yannis Milios ha scritto:
> Sorry for interrupting, but I wanted to share my experience with this as 
> well (see below) ...

thanks Yannis, it seems we are quite in sync with our trials :-)

>     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.

oh, nice

> 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?

I agree, but afaik drbd service should be the alternative mechanism for 
bringing resources up. In my experience this didn't worked.

> 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".

Same here.

> 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.

This is just what came to my mind as a solution, but what storage pool 
you used for controller vm resource? Is it the linstor-managed one or 
another? In the former case, i guess that the controller vm resource is 
a sort of 'foreign body'.

Thanks,
rob