VI3.5U2 RDM mapping files... OK to be stored with VMs?

[stensness]

Hello,

I have a HA/DRS cluster of 3 hosts, all running3.5U2 (Build 113339). I upgraded the hosts to this level a couple of weeks ago, then upgraded VirtualCenter to 3.5U2 last week. Everything is working fine.

On this cluster, among other things, I have two RHEL4 VMs sharing a raw LUN presented through our FC SAN. Each of the two RHEL4 VMs has their own RDM file stored with each VM. So, for the two RHEL4 VMs (host1 and host2), the two RDM files are:

/vmfs/volumes/vm-lun/host1/host1_1.vmdk

/vmfs/volumes/vm-lun/host2/host2_1.vmdk

So, both of the above files map to the same raw device.

I see in the release notes for 3.5U2 that "Virtual Machines Cannot Share a Raw LUN By Using Two Different RDM Files Unless RDM Filters Are Turned Off". The release notes suggest turning RDM filters off by modifying /etc/vmware/hostd/config.xml on the ESX hosts and also turning off RDM filtering in the VirtualCenter server, but neither of these measures are in place on my cluster. I haven't had any problems since the update to 3.5U2.

I'm about to set up another pair of VMs (this time running RHEL5) that will share physical LUNs in this manner, so I'm wondering... should I point both VMs at a single RDM? Should I also change the existing RHEL4 VMs so that they point to a single RDM?

Thanks...

[malaysiavm]

if you need that features to achieve what you 1, then you should try the solution you suggested above. My experience in MCSC, I did have 2 VMs connected to same physical LUN, but only 1 at active as usual and it works perfectly.

Malaysia VMware Communities -

[Texiwill · Accepted solution]

Hello,

Moved to VI: Virtual Machine and Guest OS forum.

Also, review the Virtual Hardware setup in http://www.vmware.com/pdf/vi3_35/esx_3/vi3_35_25_u1_mscs.pdf for any shared disk cluster including RHEL CLustering.

Best regards,

Edward L. Haletky

VMware Communities User Moderator

====

Author of the book 'VMWare ESX Server in the Enterprise: Planning and Securing Virtualization Servers', Copyright 2008 Pearson Education.

CIO Virtualization Blog: http://www.cio.com/blog/index/topic/168354

As well as the Virtualization Wiki at http://www.astroarch.com/wiki/index.php/Virtualization

[stensness]

OK, thanks folks, the MSCS guide does indeed say (in the appendix) that "a single, shared RDM mapping file for each clustered disk is required".

I adjusted the configuration on the ESX servers yesterday as per the instructions in the Release Notes, and was then able to use vmkfstools to make a second mapping file for the raw devices. I tried putting the relevant property in the VirtualCenter server configuration as per the instructions in the Release Notes, but it wouldn't stick, so I was still unable to do this through VC. Oh well... guess I should change to using just one mapping file.