ZFS volume inaccessible after reboot

[EvilGenius]

Hello,

since yesterday I was using Freenas 0.7. I thought upgrading to 8 would be a nice idea. So I installed version 8, created a ZFS volume (mirror with 2 WD EARS 2TB). To create the volume I had to execute 'sysctl kern.geom.debugflags=0x10', otherwise the system told me I could not create a GPT record.
After that, I configured the system and copied some GB of data onto the system.

Now, after a reboot, FreeNAS can not access the ZFS volume. It says (from dmesg):

Code:

ada0 at ata2 bus 0 scbus0 target 0 lun 0
ada0: <WDC WD20EARS-00MVWB0 51.0AB51> ATA-8 SATA 2.x device
ada0: 300.000MB/s transfers (SATA 2.x, UDMA5, PIO 8192bytes)
ada0: 1907729MB (3907029168 512 byte sectors: 16H 63S/T 16383C)
da0 at umass-sim0 bus 0 scbus4 target 0 lun 0
da0: <Mass Storage Device \\001\\000\\000?> Removable Direct Access SCSI-0 device 
da0: 40.000MB/s transfers
da0: 3826MB (7837695 512 byte sectors: 255H 63S/T 487C)
ada1 at ata3 bus 0 scbus1 target 0 lun 0
ada1: <WDC WD20EARS-00MVWB0 51.0AB51> ATA-8 SATA 2.x device
ada1: 300.000MB/s transfers (SATA 2.x, UDMA5, PIO 8192bytes)
ada1: 1907729MB (3907029168 512 byte sectors: 16H 63S/T 16383C)
GEOM: da0s1: geometry does not match label (16h,63s != 255h,63s).
GEOM: ada0: the secondary GPT table is corrupt or invalid.
GEOM: ada0: using the primary only -- recovery suggested.
GEOM: ada1: the secondary GPT table is corrupt or invalid.
GEOM: ada1: using the primary only -- recovery suggested.
GEOM_MIRROR: Device mirror/mirror0 launched (2/2).
GEOM: mirror/mirror0: corrupt or invalid GPT detected.
GEOM: mirror/mirror0: GPT rejected -- may not be recoverable.

As I have no backup anymore (stupid me, I know), is there any way to get my data accessible again? It was accessible without problem until I rebooted.

I already set the 'kern.geom.debugflags=0x10' to be enabled during bootup (and checked it is really set), no help.

Thanks in Advance,
Jan