KB1008130: VMware ESX and ESXi 3.5 U3 I/O failure on SAN LUN(s) and LUN queue is blocked indefinitely
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:
- Fibre channel SAN storage with multipathing
- A fibre channel SAN path failure or planned path transition
- Metadata update occurring during the fibre channel SAN path failure where metadata updates include but are not limited to:
- Power operations of a VM
- Snapshot operations of a VM (think backups)
- Storage VMotion (sVMotion)
- Changing a file’s attributes
- Creating a VMFS volume
- 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.
He also has the letter from VMware Here on the source post.
Thanks to Jason.