Boot multipath

[jamcguire123]

Hi there,

Undertook a recent UCS B200 deployment whereby the blade is configured to boot ESXi from an iSCSI lun, and has 2 paths, one via each FI.

Noticed in the event of FI failure I see a host error similar to:

"Lost connectivity to the device backing the boot filesystem. As a result, host configuration changes will not be saved to persistent storage."

Realised that I can use the RecoveryTimeout parameter under the iSCSI software HBA, so in the event of a storage failover, I do not see this error since the storage masquerades as the same path once it has recovered.  However if I lose an FI I lose the path altogether, therefore it will not recover and apparently there is no ability to reconnect the boot LUN via the alternate path on the second FI.

The end result is the host will continue to run. And I do have the ability to reboot the host and have it boot from the second path, but there is no dynamic ability for the host to reconnect the LUN via the second path.

All the documentation I read states that multipathing a boot LUN is unsupported, however a lot of this documentation is one or more years old, is this still the case?  Will this change in the future?

Many thanks.

[Gortee]

I cannot speak to the future since I don't work for VMware.  Since ESXi runs in memory this condition is not a major problem assuming you have setup a persistent scratch location. 

VMware KB: Creating a persistent scratch location for ESXi 4.x and 5.x

You should also use a syslog system.  All the LUN's except the boot drive should be multipathed to your storage so loss of this lun is not a problem.   Since VMware does not consider this an issue I doubt it will be fixed anytime soon just my two cents.

Thanks,

J