Forum
Welcome, Guest
Username: Password: Remember me
This is the optional category header for the Suggestion Box.

TOPIC:

NoSAN HA-ISCSI Thin Provisioning 2 weeks 6 days ago #2542

  • Salvatore Costantino
  • Salvatore Costantino's Avatar
  • Offline
  • Posts: 703
I think the below changes in 2 files would be enough to start testing. This would of course require that NFS server is installed in dom0 and the /etc/exports file is properly configured to allow mounts from both hosts.

/etc/iscsi-ha/iscsi-ha.conf
change
ISCSI_TARGET_SERVICE=tgtd
to
ISCSI_TARGET_SERVICE=nfs

/etc/iscsi-ha/iscsi-ha.conf
search the file for 2 instances of "service_execute tgtd"
and change them to "service_execute nfs"

Please Log in or Create an account to join the conversation.

NoSAN HA-ISCSI Thin Provisioning 2 weeks 6 days ago #2543

  • Maxwell Morris
  • Maxwell Morris's Avatar Topic Author
  • Offline
  • Posts: 9
Amazing! Thank you for your help Salvatore, I will make these changes, do some testing tonight and feedback any results

Please Log in or Create an account to join the conversation.

NoSAN HA-ISCSI Thin Provisioning 2 weeks 6 days ago #2544

  • Maxwell Morris
  • Maxwell Morris's Avatar Topic Author
  • Offline
  • Posts: 9
So little update, I've hit a speed bump.

In order for the NFS storage to be replicated, it of course needs to sit on top of DRBD instead of iSCSI. The issue being that in order to create an NFS share in this scenario, we need to create a filesystem on the DRBD resource that can then be mounted by the Primary node in order to then start up the NFS server. I'm working through some theories on how best to achieve this, but I'm coming up short. The only thing I can think of is to create a new systemd unit which HALizard interacts with, will mount/umount the DRBD backed filesystem and then relay start/stop commands to NFS.service.

I will give this a go in the morning, but if you have a better suggestion please let me know and I'll happily give it a go.

Cheers,
Maxwell

Please Log in or Create an account to join the conversation.

NoSAN HA-ISCSI Thin Provisioning 2 weeks 5 days ago #2545

  • Salvatore Costantino
  • Salvatore Costantino's Avatar
  • Offline
  • Posts: 703
I think you are on the right track. Regarding mounting/unmounting through systemd, I've done that before for ram disks controlled by systemd on boot and it works well.

If I recall correctly, 2 unit files were required. One .service file similar to any service file that controls a service and one .mount which handles the mounting of the filesystem

Please Log in or Create an account to join the conversation.

NoSAN HA-ISCSI Thin Provisioning 1 week 6 days ago #2546

  • Maxwell Morris
  • Maxwell Morris's Avatar Topic Author
  • Offline
  • Posts: 9
Hi Salvatore,

I was able to get NFS over DRBD working, and now have the mounting/unmounting and start/stop of NFS working between the 2 Xen nodes. From my so far simple testing (and I do truly mean simple) the VMs do seem to be noticeably slower on NFS compared to iSCSI, but this could be simply that I have missed some tuning as I am not too familiar with NFS.

I did a quick test of starting an SCP transfer to a VM, changed the cluster master twice during the transfer and it seems to have worked. Transfer paused for maybe 15-20 seconds whilst NFS spun up on the new node, but in the end the SHA256 did match.

Please let me know if there are any other tests you could recommend, or tuning options to improve the NFS performance.

Thanks!
Maxwell

Please Log in or Create an account to join the conversation.

NoSAN HA-ISCSI Thin Provisioning 1 week 6 days ago #2547

  • Salvatore Costantino
  • Salvatore Costantino's Avatar
  • Offline
  • Posts: 703
Hi Maxwell,
Looks like you've made some significant progress. I have never used NFS as storage backend for VMs, so I really don't know how much of a performance hit to expect.
One thing I would look at is the underlying filesystem you created which sits below NFS. Maybe there are better options that could improve performance.

Please Log in or Create an account to join the conversation.