OpenVZ Containers and DRBD

[fcolin]

Hi i've a short question

why we cannot use a new LVM group to store the OpenVZ Containers

Thanks

 

[dietmar]

Because openvz does not support using devices as root.

 

[xldata]

Because openvz does not support using devices as root.

I understand openvz can not work directly with devices... But it should be possible when I install a filesystem on a volume ?

My idea is to use DRBD, LVM on top of it... for the kvm's proxmox will create the lv's.... But I would like to manually create one lv myself with an ext3 on top of it for storing the OpenVZ vm's... That's possible right ?

The main question is is it possible to migrate an OpenVZ container that is replicated through the underlying DRDB in this case ? I guess shutting the container down and start it on the replicated node shouldn't be a problem ?

 

[dietmar]

My idea is to use DRBD, LVM on top of it... for the kvm's proxmox will create the lv's.... But I would like to manually create one lv myself with an ext3 on top of it for storing the OpenVZ vm's... That's possible right ?

yes, I guess it is.

The main question is is it possible to migrate an OpenVZ container that is replicated through the underlying DRDB in this case ? I guess shutting the container down and start it on the replicated node shouldn't be a problem ?

yes, should work also. But you need to copy the config files too.

 

[xldata]

Alright, great... I guess the configs can be on a DRBD replicated volume as well, symlinked to from the original location... or synced by cron + rsync

I guess the clustering part in Proxmox prevents starting a container on two hosts ? Is it also possible to migrate containers using a DRBD setup ? As far as I understood normally it will sync the filesystems data to the other node...does it still do that or does it understand the data is already there ?

I also was thinking about a slightly different setup... At the moment we have four servers reserved for setting up a proxmox ve environment... I could take two pairs of servers and make both pairs redundant in data...that's great but it will cost me a second server for each server to make it redundant...

I was thinking to have one server as spare for the other three... So the spare server get's 3 DRDB devices, of course the same size and specs of the DRBD device of the three active servers... So all three nodes replicate to that one spare node... If I need to update software or something I temporalily migrate everything to the spare, same for outages, start it all on the spare...Do you see any problems in a setup like that ?

 

[dietmar]

I guess the clustering part in Proxmox prevents starting a container on two hosts ?

Yes, because the config file is always on one host only. If you do it like your way it will not work, i.e. then you can start the vm on both nodes!

Is it also possible to migrate containers using a DRBD setup ? As far as I understood normally it will sync the filesystems data to the other node...does it still do that or does it understand the data is already there ?

it will do rsync anyways - destroying your filesytem. very dangersour setup IMO.

 

[xldata]

So it would be best not to migrate (or with a customized version of the vzmigrate script) but to stop it on the first host and start it on the second ?

What about my idea to have one server as spare for a few nodes ?