Re: [ovirt-users] question regarding fencing proxies
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 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 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? >> ___ >> Users mailing list >> Users@ovirt.org >> http://lists.ovirt.org/mailman/listinfo/users > > ___ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users
Re: [ovirt-users] question regarding fencing proxies
Il 14/Gen/2017 13:08, "Martin Perina" ha scritto: 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) Ok 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 Ok. I presume that from the list of step 6 you exclude the hosts you got from step 1 that are a subset of it. Otherwise you risk to try fence from an host that already failed three times to do so... ___ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users
Re: [ovirt-users] question regarding fencing proxies
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 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? > ___ > Users mailing list > Users@ovirt.org > http://lists.ovirt.org/mailman/listinfo/users > ___ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users
[ovirt-users] question regarding fencing proxies
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? ___ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users
