Aligning VMware VMFS on ZFS

[David Newman]

Greetings. I am trying to use 8.0-RELEASE, ZFS and the istgt port as an
iSCSI target for VMware ESX virtual machines.

A vSphere client (the management box that looks after VMware hosts and
VMs) sees the target just fine, but the FreeBSD machine returns
alignment error messages like these after the vSphere box formats a VMFS
datastore:

May 6 14:29:15 bettini kernel: GEOM: zvol/tank/bettini0: partition 1
does not start on a track boundary.
May 6 14:29:15 bettini kernel: GEOM: zvol/tank/bettini0: partition 1
does not end on a track boundary.

These errors occur only after formatting the VMFS datastore from the
VMware vSphere 4 client. The errors occur on bootup and on restarting istgt.

Steps I've already tried:

- using this guide for ZFS setup:

http://wiki.freebsd.org/RootOnZFS/GPTZFSBoot/RAIDZ1

- rebuilding so that ZFS partition starts on block 128 and ZFS partition
size is a multiple of 512 and 8192, e.g.:

bettini# gpart show da0
=>        34  1953103805  da0  GPT  (931G)
          34          94    1  freebsd-boot  (47K)
         128  1944584192    2  freebsd-zfs  (927G)
  1944584320     8388608    3  freebsd-swap  (4.0G)
  1952972928      130911       - free -  (64M)

- defining different volume sizes in ZFS ranging from 512G to 2T. I'm
currently using a 1-Tbyte ZFS filesystem as the iSCSI target. (There are
8 disks using raidz1 on this system, so available space is much higher
than the 927G shown above.)

- contacted the maintainer of istgt port, who suggests a possible VMFS
and GEOM problem such as GEOM not recognizing the VMFS format.

Thanks in advance for clues on getting VMFS aligned on ZFS.

dn