ok, so it looks like ovirt is creating PVs, VGs, and LVs associated to a iSCSI disk ... now, when i try to add the other storage with the same LUN ID - this is how it looks like :

[root@TESTHV01 ~]# pvs
  /dev/mapper/1IET_00010001: lseek 73266102272 failed: Invalid argument
  /dev/mapper/1IET_00010001: lseek 73266102272 failed: Invalid argument
  WARNING: Volume Group 7d0f78ff-aa25-4b64-a2ea-c8a65beda616 is not consistent
  PV                        VG                                   Fmt  Attr PSize   PFree
  /dev/mapper/1IET_00010001 7d0f78ff-aa25-4b64-a2ea-c8a65beda616 lvm2 a--   68.00g 54.12g
  /dev/sda2                 vg_root                              lvm2 a--   78.12g     0
  /dev/sda3                 vg_vol                               lvm2 a--  759.26g     0

[root@TESTHV01 ~]# vgs
  /dev/mapper/1IET_00010001: lseek 73266102272 failed: Invalid argument
  /dev/mapper/1IET_00010001: lseek 73266102272 failed: Invalid argument
  /dev/mapper/1IET_00010001: lseek 73266102272 failed: Invalid argument
  /dev/mapper/1IET_00010001: lseek 73266102272 failed: Invalid argument
  /dev/mapper/1IET_00010001: lseek 73266102272 failed: Invalid argument
  WARNING: Inconsistent metadata found for VG 7d0f78ff-aa25-4b64-a2ea-c8a65beda616 - updating to use version 20
  /dev/mapper/1IET_00010001: lseek 73266102272 failed: Invalid argument
  Automatic metadata correction failed
  Recovery of volume group "7d0f78ff-aa25-4b64-a2ea-c8a65beda616" failed.
  /dev/mapper/1IET_00010001: lseek 73266102272 failed: Invalid argument
  VG      #PV #LV #SN Attr   VSize   VFree
  vg_root   1   2   0 wz--n-  78.12g    0
  vg_vol    1   1   0 wz--n- 759.26g    0

[root@TESTHV01 ~]# lvs
  /dev/mapper/1IET_00010001: lseek 73266102272 failed: Invalid argument
  /dev/mapper/1IET_00010001: lseek 73266102272 failed: Invalid argument
  /dev/mapper/1IET_00010001: lseek 73266102272 failed: Invalid argument
  /dev/mapper/1IET_00010001: lseek 73266102272 failed: Invalid argument
  /dev/mapper/1IET_00010001: lseek 73266102272 failed: Invalid argument
  WARNING: Inconsistent metadata found for VG 7d0f78ff-aa25-4b64-a2ea-c8a65beda616 - updating to use version 20
  /dev/mapper/1IET_00010001: lseek 73266102272 failed: Invalid argument
  Automatic metadata correction failed
  Recovery of volume group "7d0f78ff-aa25-4b64-a2ea-c8a65beda616" failed.
  Skipping volume group 7d0f78ff-aa25-4b64-a2ea-c8a65beda616
  /dev/mapper/1IET_00010001: lseek 73266102272 failed: Invalid argument
  LV      VG      Attr     LSize   Pool Origin Data%  Move Log Copy%  Convert
  lv_root vg_root -wi-ao--  68.36g                                          
  lv_swap vg_root -wi-ao--   9.77g                                          
  lv_vol  vg_vol  -wi-ao-- 759.26g                                          

Ovirt Node ( HV ) seems to use the LV created with in the same VG for the storage domain as the disk for the VM. And this is how it'll look like - various LVs are being created for the "management of the storage domain" (i guess) :

Disk /dev/sdb: 73.4 GB, 73400320000 bytes
255 heads, 63 sectors/track, 8923 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000


Disk /dev/mapper/1IET_00010001: 73.4 GB, 73400320000 bytes
255 heads, 63 sectors/track, 8923 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000


Disk /dev/mapper/7d0f78ff--aa25--4b64--a2ea--c8a65beda616-metadata: 536 MB, 536870912 bytes
255 heads, 63 sectors/track, 65 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000


Disk /dev/mapper/7d0f78ff--aa25--4b64--a2ea--c8a65beda616-ids: 134 MB, 134217728 bytes
255 heads, 63 sectors/track, 16 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000


Disk /dev/mapper/7d0f78ff--aa25--4b64--a2ea--c8a65beda616-leases: 2147 MB, 2147483648 bytes
255 heads, 63 sectors/track, 261 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000


Disk /dev/mapper/7d0f78ff--aa25--4b64--a2ea--c8a65beda616-inbox: 134 MB, 134217728 bytes
255 heads, 63 sectors/track, 16 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000


Disk /dev/mapper/7d0f78ff--aa25--4b64--a2ea--c8a65beda616-outbox: 134 MB, 134217728 bytes
255 heads, 63 sectors/track, 16 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000


Disk /dev/mapper/7d0f78ff--aa25--4b64--a2ea--c8a65beda616-master: 1073 MB, 1073741824 bytes
255 heads, 63 sectors/track, 130 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000


Disk /dev/mapper/7d0f78ff--aa25--4b64--a2ea--c8a65beda616-fe6f8584--b6da--4ef0--8879--bf23022827d7: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0000c91a

                                                                                         Device Boot      Start         End      Blocks   Id  System
/dev/mapper/7d0f78ff--aa25--4b64--a2ea--c8a65beda616-fe6f8584--b6da--4ef0--8879  *           1          64      512000   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/mapper/7d0f78ff--aa25--4b64--a2ea--c8a65beda616-fe6f8584--b6da--4ef0--8879             64        1306     9972736   8e  Linux LVM

Now I wonder whether there is a MAX on the amount of iSCSI storage domains you can have ? I'd think that that depends on the max of the device-mapper ? Is there a max ?

Alex