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Installation on Xenserver 7 hosts with existing VM 6 years 11 months ago #1291

  • Mauritz
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We have 2 xenserver 7 hosts with existing VM's on them. From what I have read online it appears that HAL only works with newly installed hosts and that installing HAL on the existing hosts may delete meta data for these vm's which is the last thing we want :)

If the above is correct, what options do we have? I'm leaning towards the setup a temp 3rd host to move all our VM's to, then formatting the 2 hosts, setup the pool, HA and then adding the new temp host to the pool and then move the VM's back to the respective hosts. Is this the recommended installation for existing hosts or is there another option?

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Installation on Xenserver 7 hosts with existing VM 6 years 11 months ago #1293

When I first installed HA-Lizard myself I just moved my VMs to temporary shared storage on a NAS, then moved them to the new iSCSI drive after installation was finished. You will lose anything that is still on the local storage point which is getting converted to shared iSCSI storage. The temp third host will work too, but isn't actually necessary. I didn't have any downtime with the way I did it.

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Installation on Xenserver 7 hosts with existing VM 6 years 10 months ago #1296

  • Mauritz
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Our current setup has the 2 hosts running local storage. We also have a 3rd host which I currently have NFS storage setup. Both of the xen hosts has access to the NFS storage.

If I understand you correctly the following should then work:

1. Move all of the vm's on one of the hosts to the NFS storage.
2. Install HA-Lizard which will then configure all of the available LOCAL storage as HA storage. All data on the local storage will then be cleared but all of the VM's on the NFS storage will still run without an issue.
3. Move all of the VM's back to the HA storage
4. Follow the same with the 2nd hosts

Would this work and will the VM's be safe?

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Installation on Xenserver 7 hosts with existing VM 6 years 10 months ago #1297

Close. If you look at their PDF reference guide and watch the video, which I found very helpful, you'll see that he installs HA-Lizard on both servers at the same time. I would move ALL of your VMs from both XenServers to NFS storage so you can work with both of them together.

The default HA-Lizard install script will only take one drive on each machine, not necessarily ALL local storage like you mentioned above. I just added a second set of drives to my servers and created another iSCSI drive too, but I suspect you have just one local storage repository on each server.

One thing to understand - XenServer stays up and running while you're installing HA-Lizard. As long as there aren't any VMs on the disks you are working with nothing gets lost and there is zero downtime.

So what I would do is:
1. Move all VMs from both servers to NFS storage (or any external point.)
2. Install HA-L using the install script on both XenServers.
2a. Let them finish syncing, which can take a long time (I let my new 4TB drives sync overnight.) You don't HAVE to do this but I like to make sure everything is working perfectly before utilizing the iSCSI drive.
3. Move all VMs onto the new iSCSI drive.
4. There is no step 4.

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Installation on Xenserver 7 hosts with existing VM 6 years 10 months ago #1298

  • Mauritz
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Thank you for your help so far Bill! I have considered this but worried that the NFS might be too slow (gigabit network) to run all of the VM's on (there is about 10 at the moment) - I have not tested the durability but have not read a lot of success stories over gigabit lan?

Also further regarding storage, each server has multiple storage repositories (each server has both SATA and SSD storage) which is setup as seperate SR's so that we can control if a VM should be on SSD or SATA. If I understand correctly, does this mean that HA will only use 1 SR and the rest will be untouched?

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Installation on Xenserver 7 hosts with existing VM 6 years 10 months ago #1299

I've used NFS over gigabit network a couple times on small networks with OK results. But if you have multiple disks in your XenServers and enough space there's may be a better way. Just clear off one set of SRs (same size on each XenServer) and install HAL. Make sure you know which disk you're using so you don't wipe out the wrong local SR.

Then, after the first iSCSI drive is ready, move all your VMs there and reconfigure the other set of disks for HAL. Then move your VMs around to where you finally want them to be. There are other threads on here about adding a second iSCSI drive and I can post my own config files that I know work on XS 7 since I just did it earlier this week.

The only downtime I ended up with was a reboot of each server after reconfiguring for the second iSCSI drive but that was minimal.

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