"Unable to read partition information from this disk"

26 04 2009

The VI Client gave me this error when I tried to add a newly presented lun:

“Unable to read partition information from this disk”

Logging into one of the ESX hosts that has had this lun presented I can see the device is attached with the ‘esxcfg-mpath -l’ command, but a ‘esxcfg-vmhbadevs -m’ fails to show the associated vmfs volume (as there isn’t one).

Fix: I was able to rebuild the partition tables and format the lun using directions I found in this thread from Chamon:

Note: I had to delete all existing partitions on the lun and then use the ‘o’ option in fdisk on the device to rebuild the partition tables before I could use the directions below.

1. On service console, execute fdisk /dev/sd where sd is the device on which you would like to create the VMFS.
2. Type “n” to create a new partition.
3. Type “p” to create a primary partition.
4. Type “1” to create partition #1.
5. Select the defaults to use the complete disk.
6. Type “x” to get into expert mode.
7. Type “b” to specify the starting block for partitions.
8. Select partition #1.
9. Type “128” to make partition #1 to align on 64KB boundary.
10. Type “r” to return to the main menu.
11. Type “t” to change partition type.
12. Type “1” to select partition #1.
13. Type “fb” to set the type to fb (VMFS volume).
14. Type “w” to write label and the partition information to disk.

After following these steps I was able to add the lun through the VI client!

EDIT: Since upgrading to ESXi, I have had to add a couple of steps:

1. Logon to console of host
2. Hit alt-f1, then type “unsupported”, hit enter, and enter root password to gain access to the hidden console
3. complete above steps (note that the “sd*” notation is gone now that there is no linux console, so it is now /vmfs/devices/disks/….)
4. Hit alt-f2 once complete to get out of the hidden console




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