ISCSI SAN and Vmotion question

[rabih_00]

Hello,

I am now in the process of implementing VI3. how does it work with Vmotion and DRS.

1 lun is shared among 2 machines, and many virtual machines are running. which hosts will be the owner of that LUN? what happens when we vmotion a machine? we wil end up with 2 hosts writing to the same lun??

How does ESX do it to manage that?

Thanks

[Dave_Mishchenko · Accepted solution]

Both servers will share the LUN and use file level locks to control access to the files for a particular VM.

See page 32 and following here: http://www.vmware.com/pdf/vi3_esx_san_cfg.pdf

Here's a PDF with the basics of how Vmotion accomplishes the migration to another host: http://www.vmware.com/pdf/vmotion_datasheet.pdf

[christianZ]

Basically vmotion works similar with iscsi as with fc.

You can do it on vmfs volume which is shared between the (min.) 2 hosts - the vmdk files will be not moved but only the vm's assignment will be changed from one host to another thereby the ram of the vm will be moved into the other esx host.

All this is possible because the vmfs is a type of cluster file system which can control the access from many hosts.

Hope that's clear.

[Paul_Lalonde]

The ESX servers all share the iSCSI LUN. As ChristianZ says, VMFS is a cluster file system so all the multi-node arbitration is taken care of.

As for VMotion and accessibility to virtual machines, each ESX server simply maintains a pointer to each VM. No one ESX server actually owns (or controls) a virtual machine... just points to it.

Paul