I'm running snv_101a and have been seeing some unexpected behaviour with ZFS
and EFI disk labels.
If I fdisk 2 disks to have EFI partitions and label them with the appropriate
partition beginning at sector 34 and then give them to ZFS for a pool, ZFS
would appear to change the beginning sector to 256. I've even done a low-level
format to make sure that this wasn't a case of ZFS picking up an old vdev label
from the back-end of the disk and preserving it in the front for some unknown
reason.
I've looked through the ZFS technical documentation and around the net and have
found nothing that would explain this behaviour. The vdev labels are 256k * 2
in front, but if I'm doing my math properly, the 256 sectors only comes to 128k
of space so it can't be a lingering vdev label. Not to mention that the prtvtoc
claims that the space between sector 34 and 255 is unallocated, e.g.
* /dev/rdsk/c0t3d0s2 partition map
*
* Dimensions:
* 512 bytes/sector
* 286494720 sectors
* 286494653 accessible sectors
*
* Flags:
* 1: unmountable
* 10: read-only
*
* Unallocated space:
* First Sector Last
* Sector Count Sector
* 34 222 255
*
* First Sector Last
* Partition Tag Flags Sector Count Sector Mount Directory
0 4 00 256 286478047 286478302
8 11 00 286478303 16384 286494686
So, have I found a bug? A feature? It would appear to be a harmless waste of
space but at the very least I'd like to know why ZFS is doing this.
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