topic 2 servers with access to the same EVA lun in Operating System - Linux

2 servers with access to the same EVA lun

westb — Fri, 11 Sep 2009 14:53:49 GMT

I've done this before with solaris and am wondering if there are any gotchas in linux.

SAN=HP EVA 8100
2 Servers=HP BL685 with Qlogic HBA
OS=RHEL5.3 AP + Xen virtualization

Okay, I've got one single lun that is presented to one of the BL685 servers. This in turn is attached to a xen guest as a simple block device.

What I want to do is have a second BL685 have access to the same lun; basically I just want it attached to the dom0 of the second server and be available in terms of cold migration

I really just want to do a cold migration from one dom0 to another but I want everything in place to make the process simpler and faster.

From the EVA, can I just present the lun to a second server and then, just scan the bus for the new lun? Also, on the second server I will have a copy the domU config file located in /etc/xen.

So, if the first server is down for any reason, I should be able to "xm create domU-guest" on the second server and have the guest come up right ?

Anything wrong with this ?

Thx.

Re: 2 servers with access to the same EVA lun

skt_skt — Sat, 12 Sep 2009 13:17:03 GMT

As long as "you are verifying" the LUNS not used at the same time on both the servers you should be ok. When ever you miss that then you are at risk of data lose

Re: 2 servers with access to the same EVA lun

Jimmy Vance — Mon, 14 Sep 2009 02:29:59 GMT

In theory what your wanting to do should work. Just remember if both systems are up and write to the LUN your data will be corrupted.

You might look at running the Citrix version of XenServer as it allows you to put servers in pools using shared storage. The automated HA in Citrix XenServer is fee based as it is in the enterprise version, but the free version of Citrix XenServer allows you to setup VM's in pools and manually fail them over. Citrix XenServer 5.5 is based on CentOS 5.3 so the environment you'd be working with is similiar to what you have now

Re: 2 servers with access to the same EVA lun

Alzhy — Mon, 14 Sep 2009 17:45:39 GMT

Jimmy is correct.

What you're wanting to do entails a huge Caveat Emptor though amigo.