Solaris: Identifying EFI disks

EFI label supports physical disks and logical volumes that are > 2 TB in size. SMI support is limited to 2 TB.

Listed below are some of the characteristics and patterns that can help identify and differentiate an EFI labeled disk from a SMI labeled disk.

• Device cxtxd0 [without any slice suffix] represents the entire disk

• No cylinder information is stored in the EFI label.

• No overlapping slices / partitions

  • eg.,

    EFI label disk:

    Notice that there are no overlapped partitions and no references to cylinders in the following prtvtoc output.

    % prtvtoc /dev/rdsk/c0t5000CCA04E0DEDD8d0
    * /dev/rdsk/c0t5000CCA04E0DEDD8d0 partition map
    *
    * Dimensions:
    *     512 bytes/sector
    * 390721968 sectors
    * 390721901 accessible sectors
    *
    * Flags:
    *   1: unmountable
    *  10: read-only
    *
    * Unallocated space:
    *       First     Sector    Last
    *       Sector     Count    Sector
    *          34         6        39
    *   390070312    635239 390705550
    *
    *                          First     Sector    Last
    * Partition  Tag  Flags    Sector     Count    Sector  Mount Directory
           0      4    00         40   2097152   2097191
           1      4    00    2097192 384827392 386924583
           4      4    00  386924584   3145728 390070311
           8     11    00  390705551     16384 390721934
    

    SMI label disk:

    Notice the overlapped partitions (0 & 2. also 2 & 6) and references to cylinders in the following prtvtoc output.

    # prtvtoc /dev/rdsk/c0t5000A72030082BD5d0s2
    * /dev/rdsk/c0t5000A72030082BD5d0s2 partition map
    *
    * Dimensions:
    *     512 bytes/sector
    *      56 sectors/track
    *     224 tracks/cylinder
    *   12544 sectors/cylinder
    *   11429 cylinders
    *   11427 accessible cylinders
    *
    * Flags:
    *   1: unmountable
    *  10: read-only
    *
    *                          First     Sector    Last
    * Partition  Tag  Flags    Sector     Count    Sector  Mount Directory
           0      2    00          0    263424    263423
           1      3    01     263424    263424    526847
           2      5    01          0 143340288 143340287
           6      4    00     526848 142813440 143340287
    

• Existence of /dev/[r]dsk/cxtxd0 implies EFI label. In case of SMI label, /dev/[r]dsk/cxtxd0 won't exist.

  • eg.,

    EFI label disk:

    % ls /dev/rdsk/c0t5000CCA04E0DEDD8d0
    /dev/rdsk/c0t5000CCA04E0DEDD8d0
    

    SMI label disk:

    # ls /dev/rdsk/c0t5000A72030082BD5d0
    /dev/rdsk/c0t5000A72030082BD5d0: No such file or directory
    

• The presence of "wd" (whole disk?) in device path of the physical device may imply EFI label.

  • eg.,

    EFI label disk:

    % stat -c "%N" /dev/rdsk/c0t5000CCA04E0DEDD8d0
    ‘/dev/rdsk/c0t5000CCA04E0DEDD8d0’ -> ‘../../devices/scsi_vhci/disk@g5000cca04e0dedd8:wd,raw’
    

    SMI label disk:

    # stat -c "%N" /dev/rdsk/c0t5000A72030082BD5d0s2
    '/dev/rdsk/c0t5000A72030082BD5d0s2' -> '../../devices/scsi_vhci/disk@g5000a72030082bd5:c,raw'
    

• As of this writing, devinfo(1M) does not support EFI labeled disks.

  • eg.,

    EFI label disk:

    % devinfo -i /dev/rdsk/c0t5000CCA04E0DEDD8d0
    devinfo: /dev/rdsk/c0t5000CCA04E0DEDD8d0: This operation is not supported on EFI labeled devices
    

    SMI label disk:

    # devinfo -i /dev/rdsk/c0t5000A72030082BD5d0s2
    /dev/rdsk/c0t5000A72030082BD5d0s2       0       0       12544   512     4
    

Credit: various internal sources