3 nodes cluster+High Availability+ iSCSI storage/LVM+online backup for Openvz CT's ?

R

Ruben Waitz

Member
Aug 6, 2012
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Hi everybody,

I'm new to this forum and this is my first post.
I've become stuck in a High Availability cluster setup with an iSCSI datastorage back-end.

NFS
For a couple of weeks I've a 3-nodes Proxmox VE 2 High Availability cluster running. For datastorage I used a separate NFS-server, which works fine, I thought...
The only problem with this setup is running online backups. This is because NFS can't be mounted as a LVM volume with snapshots, if I'm right.

So my next thought was moving to iSCSI.

iSCSI target
Based on this article (http://eugenyho.blogspot.nl/2012/04/ha-storage-cluster-setup-process.html) I succeeded in mounting an iSCSI storage in an LVM setup. This way OpenVZ containers can run on a proxmox node with snapshot features.

The big question
Because a single iSCSI target/LUN can't be mounted/shared on multiple proxmox nodes simultaniously, High Availability is not possible (I think).

Is there another way/work-around to get OpenVZ containers running in a High Availability proxmox cluster with an iSCSI datastorage? (Online back-ups, without downtime is required).


I hope somebody can help me.
Thanks in advance!


Ruben



Used resources for my setup:
http://eugenyho.blogspot.nl/2012/04/ha-storage-cluster-setup-process.html
http://www.server-world.info/en/note?os=CentOS_6&p=iscsi
http://houseoflinux.com/high-availa...ith-nfs-v4-drbd-8-3-and-heartbeat-on-centos-6
http://www.chriscowley.me.uk/blog/2012/02/20/add-san-functions-to-highly-available-nfs-slash-nas/
http://0wned.it/geek-bits/guides/high-availability-iscsi-target-using-linux/
http://forum.proxmox.com/threads/9940-Getting-iSCSI-storage-working-with-proxmox
 
Re: 3 nodes cluster+High Availability+ iSCSI storage/LVM+online backup for Openvz CT'

Online backups of openvz using NFS should work quite well (without LVM) using suspend mode. And problems with that?
 
Last edited:
Re: 3 nodes cluster+High Availability+ iSCSI storage/LVM+online backup for Openvz CT'

Dear Dietmar,

Thank you for your quick reply.

I will enable NFS again to test again. If I recall it correctly, the backup system falls back from "online/snapshot" to "suspend" mode.
(Furthermore there are some issues with an NFS lock files. Maybe that's preventing the snapshot backup, but I'm not sure about it.)

I will come back here and post about my findings.

Best regards,
Ruben
 
Re: 3 nodes cluster+High Availability+ iSCSI storage/LVM+online backup for Openvz CT'

Dear Dietmar,

I've retried to make online backups of OpenVZ containers residing on a NFS storage, but it falls back into suspend mode.
After some digging in the forums I found your colleague Tom saying this: http://forum.proxmox.com/threads/10...t-Backups-possible-with-NFS?p=56360#post56360

The task viewer output is (ha-storage is the mounted NFS storage ID):
INFO: starting new backup job: vzdump 444 --remove 0 --mode snapshot --compress lzo --storage ha-storage --node proxmox01
INFO: Starting Backup of VM 444 (openvz)
INFO: CTID 444 exist mounted running
INFO: status = running
INFO: mode failure - unable to detect lvm volume group
INFO: trying 'suspend' mode instead
INFO: backup mode: suspend
INFO: ionice priority: 7
INFO: starting first sync /mnt/pve/ha-storage/private/444/ to /mnt/pve/ha-storage/dump/vzdump-openvz-444-2012_08_07-10_53_38.tmp
Etc. etc.

Is there another way to achieve a high availability cluster connected to an external storage with OpenVZ containers and "online" backups features?

Thanks in advance!

Best Regards,
Ruben
 
Re: 3 nodes cluster+High Availability+ iSCSI storage/LVM+online backup for Openvz CT'

Ruben Waitz said:
I've retried to make online backups of OpenVZ containers residing on a NFS storage, but it falls back into suspend mode.
Click to expand...

Oh sorry. I meant 'Online backups of openvz using NFS should work quite well (without LVM) using suspend mode'.

I corrected above post to avoid further confusion.

You do not want to use suspend mode? Downtime should be short.
 
Re: 3 nodes cluster+High Availability+ iSCSI storage/LVM+online backup for Openvz CT'

Thank you!

Suspend mode is sufficient for now. I was concerned that user-sessions (to a webserver on a CT) could get lost, but seemingly this is not the case.

(Maybe AoE (ATA over Ethernet) is a final solution? Assuming that mounting it on all cluster nodes won't lead to data corruption)

Best Regards,
Ruben
 
Re: 3 nodes cluster+High Availability+ iSCSI storage/LVM+online backup for Openvz CT'

Ruben Waitz said:
Thank you!

Suspend mode is sufficient for now. I was concerned that user-sessions (to a webserver on a CT) could get lost, but seemingly this is not the case.

(Maybe AoE (ATA over Ethernet) is a final solution? Assuming that mounting it on all cluster nodes won't lead to data corruption)

Best Regards,
Ruben
Click to expand...
Hi Ruben,
it's make no different if you use AoE, FC, iSCSI, DRBD or what else - if you share an blockdevice you can't mount this device with an normal filesystem on multible nodes simultanous. For this, you need an cluster-filesystem.

Udo
 
Re: 3 nodes cluster+High Availability+ iSCSI storage/LVM+online backup for Openvz CT'

Hi Udo,

Thank you for this clarification.
(If you think about it, it's quite understandable that blockdevices aren't shareable)

Ruben
 
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