Hmm, VMware and 4k disk blocks

At work we now have a very nice SAN with two machines running VMware vSphere. I did try to add fibre storage to the VMware machines and that didn’t work. I did get a lot of errors and unknown problems. Even Google never heard of them. One of those was

Error during the configuration of the host:
Failed to get disk partition information

Googling for this and more generic terms pointed me to a hint to partition the disk on the VMware server itself and then create a VMFS filesystem onto it. Well, that should be easy enough.

Running partedUtil on the device gave me:

/dev/disks # partedUtil get naa.60050cc00061071d00000000000000d9
Warning: Device /dev/disks/naa.60050cc00061071d00000000000000d9 has
a logical sector size of 4096.
Not all parts of GNU Parted support this at the moment, and the
working code is HIGHLY EXPERIMENTAL.

Segmentation fault

That seems realy broke!

I suddenly realized that I set the blocksize at the SAN level to be 4k. I did this because VMware uses very large files, so 4k should be more efficient. But it seems that VMware doesn’t support it. Why not?

Removing the logical disk on the SAN side and recreating is with a blocksize of 512 bytes completely solved the problem.

I always love it when an error message points you into the right direction.


See also