Hi Garith,

There are a few questions wrapped up in there.

WRT HA, there a number of reasons why CloudStack might not do anything as a 
result of a cable pull. For instance was the network cable you unplugged also 
carrying the primary storage? If not, then the XenServer will continue to run 
the VM and continue to send heartbeats to its shared storage. CloudStack would 
see that and decide that restarting the instance somewhere else would be 
dangerous as it could result in a split-brain.  You'll likely see in the 
CloudStack logs whether CloudStack has detected a problem and what it intends 
to do about it (if anything)

It is possible to re-add a XenServer, but it's generally more trouble than it's 
worth, there's quite a bit of cleaning up to do and you never know what legacy 
issues you're carrying over.

It's pretty much always best to rebuild it from scratch to a known state and 
re-add it.  Automated build processes are worth their weight in gold for these 
circumstances.



Regards,

Paul Angus
Cloud Architect
S: +44 20 3603 0540 | M: +447711418784 | T: @CloudyAngus
[email protected]

-----Original Message-----
From: Garith Dugmore [mailto:[email protected]]
Sent: 22 October 2014 15:54
To: [email protected]
Subject: HA issue and Xen resets

Hi All,

I'm new to cloudstack and busy testing out ACS 4.3.1 on Centos 6.4 using 
Xenserver 6.2. I have the management server setup and have 2 xen servers that 
I'm testing out at the moment; specifically the HA functionality.

After getting an instance up and running I yanked the network cable out of the 
one xen server and awaited the HA awesomeness to kick in. Both hosts still 
remained in "Up" state even though the one was no longer pingable and the 
instance that was hosted on that xen host still showed "Running" even though I 
also couldn't ping it. After some reading one suggestion was setting 
'alert.wait' to 30 and restarting cloudstack-management. After that didn't seem 
to do anything after waiting a while I rebooted the management server all 
together and found that both hosts were marked as disconnected.

I've tried going in and out of maintenance mode and ended up deleting the one 
xen host that was still reachable thinking I could just re-add it but I 
received an error in doing so. I have read somewhere that once you've either 
reinstalled the management server or removed a xen host you need to re-install 
the xen host. Is this true? I was hoping for a factory reset command of some 
sort.

Besides my obvious HA problems and host disconnect issues which I'd love some 
pointers on are there any pointers on Xen server resets?

Note I have attempted a 4.4.0 install on centos and after a couple issues that 
I can no longer recall I ended up with a way easier install on 4.3.1 which is 
why I've stuck with it for now.

Any pointers will be greatly appreciated. Willing to try anything!
--

Garith Dugmore
South African Astronomical Observatory
and Southern African Large Telescope
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