Good simple and cheap fence Setup

[MasterTH]

Hi there,

i'm searching for a cheap good and simple fence setup/device.
Maybe ifmib is a good option?

Thanks for answers

 

[tom]

APC power switches are a good choice. If you want HA you should use premium hardware on all places.

 

[MasterTH]

thanks.

i'm dealing with another problem. If one Node is powered down the service is not switched over, is this normal?? Or would it work if fencing is working correctly?

 

[spirit]

yes, you need fencing to be sure that the server is shutdown.
(to not restart vm twice if a network problem occur between your nodes)

 

[MasterTH]

but do i need a hw-fence device? i saw there's fence_ifmib.

 

[dietmar]

but do i need a hw-fence device? i saw there's fence_ifmib.

What device do you want to fence with ifmib?

 

[sengo]

ifmib only makes sense if you are using an iscsi san or nfs (on a dedicated network card). What kind of storage are you using?

 

[MasterTH]

i use nfs on a dedicated network device

 

[sengo]

i use nfs on a dedicated network device

Ok then configure fence_ifmib to shutdown the switchports on which the servers are connected to the nfs network. That's it. Of course you need a managed switch that allow snmp write access.

Scenario:
Server B crashes
Server A shuts down the switchports on which Server B is connected to the NFS network
Server A takes over

Anyway IMHO the only reliable fencing mode is power fencing with external PDU.

 

[MasterTH]

isn't it possible to shutdown ifport on the server that crashed

 

[sengo]

isn't it possible to shutdown ifport on the server that crashed

What do you mean? Please explain

 

[MasterTH]

ok i'll try.

http://honglus.blogspot.de/2011/05/rhcsred-hat-cluster-suite-io-fencing.html

i found this docu and thought this is what i need.


my plan is to setup a three node proxmoxcluster with integrated high availible storage service. Everything works fine, except the thing "what happens when power failure occurs".
The servers are rent in a datacenter so the methods for fencing are really small. APC isn't possible because the datacenter doesn't allow to install own components....