KB1008130: VMware ESX and ESXi 3.5 U3 I/O failure on SAN LUN(s) and LUN queue is blocked indefinitely

Jason Boche, @ Boche.net has a post about KB 1008130 that I wanted to share.

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KB1008130: VMware ESX and ESXi 3.5 U3 I/O failure on SAN LUN(s) and LUN queue is blocked indefinitely

by jason on Jan.19, 2009, under Virtualization

I became aware of this issue last week by word of mouth and received the official Email blast from VMware this morning.

The vulnerability lies in a convergence of circumstances:

1. Fibre channel SAN storage with multipathing
2. A fibre channel SAN path failure or planned path transition
3. Metadata update occurring during the fibre channel SAN path failure where metadata updates include but are not limited to:
   1. Power operations of a VM
   2. Snapshot operations of a VM (think backups)
   3. Storage VMotion (sVMotion)
   4. Changing a file’s attributes
   5. Creating a VMFS volume
   6. Creating, modifying, deleting, growing, or locking of a file on a VMFS volume

The chance of a fibre channel path failure can be rated as slim, however, metadata updates can happen quite frequently, or more often than you might think.  Therefore, if a fibre channel path failure occurs, chances are good that a metadata update could be in flight which is precisely when disaster will strike.  Moreover, the safety benefit and reliance on multipathing is diminished by the vulnerability.

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He also has the letter from VMware Here on the source post.

Full Source Post http://www.boche.net/blog/index.php/2009/01/19/kb1008130-vmware-esx-and-esxi-35-u3-io-failure-on-san-luns-and-lun-queue-is-blocked-indefinitely/

Thanks to Jason.