Unable to umount greyed-out datastore due to Storage I/O Control

During a storage migration the SAN team had to create and delete multiple LUNs for the VMware vSphere 5.1 environment.

Accidentally they deleted a LUN that wasn’t deleted in VMware vSphere. Gladly there were no more virtual machine on that datastore. When I tried to unmount the volume I got the following error:

Unmount failed SIOC error









The message is clear. I cannot unmount the datastore because SIOC is enabled. But I can’t disabled SIOC because the datastore ain’t available anymore. There are 2 solutions for this.

  1. Reboot the hosts. During boot SIOC won’t be enabled on the datastore anymore and you will be able to unmount the datastore.
  2. SSH to the ESXi console and stop the SIOC deamon by entering:
    /etc/init.d/storageRM stop
    Give a Rescan all on the storage adapter and enable the SIOC deamon again with the command:
    /etc/init.d/storageRM start
    Now you’re able to unmount the datastore.

Option 2 is nice if you don’t want or are unable to reboot your vSphere hosts.


About Michael
Michael Wilmsen is a experienced VMware Architect with more than 20 years in the IT industry. Main focus is VMware vSphere, Horizon View and Hyper Converged with a deep interest into performance and architecture. Michael is VCDX 210 certified, has been rewarded with the vExpert title from 2011, Nutanix Tech Champion and a Nutanix Platform Professional.

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