RE: [Xen-users] Shared SAN disk LUN between 2 servers and migration problem

[George Rushby <george@xxxxxxxxxxxxxx>]

You are connecting to the same volume with at least 2 servers. This will cause your files system to eventually corrupt. The array has no knowledge of your operating system at this level you should think of a volume as a disk drive. If you are not using a cluster you must restrict access to the volume to only one server. Once you connect to the volume you share the volume through the server. Most people will set up a server with 2 NIC's one to connect to the iscsi vlan setup for the array and the other is on the public vlan. This way you separate your traffic and are able to share the data on the volume.

 

You should also look in GFS

 

From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Pekka.Panula@xxxxxxxx
Sent: 16 October 2008 10:05 AM
To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] Shared SAN disk LUN between 2 servers and migration problem

 

HI

Dom0 is CentOS 5.2, 64-bit, Xen version 3.2.1 and 3.2.2.

I got Fiber SAN disk system and 2 servers and i am making shared LUN available to both servers. Then i got multipath layer running on both Dom0s and so Xen is seeing device-mapper file, instead of two /dev/sdX devices, then i have setup Xen domU (HVM Windows 2003) using /dev/mapper/sharedLUN as physical storage to my windows server.

Do i need one more layer to setup migration working? It seems now that if i migrate between servers i get filesystem corruptions.

Perhaps some sort of cache on Linux that it not written to disk system yet is causing this and when server is migrated device state is not same on target servers multipath device, eg. some part of write operation is not written to shared lun device so target Xen dont have complete state.

Whats the best way so cache problem do not occur, eg. both multipath devices has same state on both servers, i am not wanting to duplicate data and use anything separate cluster file system,  so is there some sort of system how to get this problem fixed?

Terveisin/Regards,
  Pekka Panula, Net Servant Oy

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