8:48 a.m.
Thanks Martin. That is what I assumed was the case, but got worried
when the host could not communicate with the idrac via the 'Test'
option in the GUI. I planned to test it when I get a chance by
migrating all VMs bar one to the other host, setting the remaining one
as HA, and then bringing that host down to see if it gets migrated
successfully. I do plan to add a 3rd host.
I was looking at adding an APC agent as well. Can you tell me whether
4.x supports 2 PDUs per host? We have diverse power on each server. I
saw a post in 2012 that only one was supported and didn't see an
option for adding two slots in the GUI.
Thanks,
Cam
On Sat, Jan 14, 2017 at 12:07 PM, Martin Perina <mperina(a)redhat.com> wrote:
Hi,
engine executes power management (fencing) operation using different host in
the same cluster/DC as target host reside. It's an oVirt requirement that
each host in the same cluster and data center is able to connect to power
management deviced of all other hosts in the same cluster/DC.
Here's simplified flow for defaults (fence proxy may be selected in the same
cluster or DC)
1. Find all existing hosts in the same cluster which don't have connection
issues (status Up, Maintenance, NonOperational for a reason different than
network issues)
2. Select first host in Up (if no host is Up, then pick any other host, if
no host found continue with DC in step 5) and try to execute fence operation
3. If fence operation is successful, exit
4. If not, retry 2 times and if still not successful go back to step 2 but
exclude already problematic fence proxy
5. Find all existing hosts in the same data center which don't have
connection issues (status Up, Maintenance, NonOperational for a reason
different than network issues)
6. Select first host in Up (if no host is Up, then pick any other host, if
no host found then fail and exit) and try to execute fence operation
7. If fence operation is successful, exit
8. If not, retry 2 times and if still not successful go back to step 6 but
exclude already problematic fence proxy
9. If still no success, fail
As you see your setup with only 2 hosts is kinda fragile (and not only for
fencing operations), you need to assure that 1 hosts is always in perfect
condition. If possible I'd recommend you to add at least one other host if
possible to make your setup more resistant to failures.
Martin Perina
On Fri, Jan 13, 2017 at 6:10 PM, cmc <iucounu(a)gmail.com> wrote:
>
> Hi,
>
> Can someone tell me how the engine decides which power management
> proxy/proxies to use (using default cluster/dc config)? I am using
> drac 7 for a fence agent in my two host cluster, and have noticed that
> one of the hosts cannot contact the drac. My guess is that the engine
> is using one host to as a power management proxy and hosts cannot
> reach their own drac as they are on the same interface + vlan.
>
> Example scenario:
>
> Engine uses host 2 as power management proxy. It can contact host 1’s
> drac, but cannot contact its own drac. In the case of host 2 being
> unreachable/kdumping etc, would the engine switch to use host 1 as the
> proxy to contact host 2’s drac?
>
> Thanks,
>
> Cam
>
> PS: I'd like to use the APC as an additional fencing agent, each host
> has two PSUs connected to two different APCs. Is there a guide on how
> to specify two ports on two different PDUs to control power on a host?
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