How to unencapsulate the rootdisk using the vxunroot script

There may be occasions when there will be a need to access the /opt file system via Solaris rather than via its volume. If this is the case, an underlying partition will have to be created so that Solaris can access the data via its slice on its respective disk. This can be achieved using a VERITAS Volume Manager tool called vxmksdpart and mapping a subdisk of the volume to a partition.

1. Determine the partition available for /opt with the prtvtoc command:

# prtvtoc /dev/dsk/c0t0d0s2

/dev/dsk/c0t0d0s2 partition map
Dimensions:
512 bytes/sector
63 sectors/track
16 tracks/cylinder
1008 sectors/cylinder
16708 cylinders
16706 accessible cylinders

Flags:
1: unmountable
10: read-only

Unallocated space:
First          Sector          Last
Sector       Count           Sector
8192016   4286775280  4294967295
16839648 4286321680   8194031
10957968  5881680       16839647

First      Sector    Last
Partition  Tag  Flags    Sector       Count        Sector   Mount Directory
   0          2     00          0           8192016    8192015
   1          3    01     8196048      713664      8909711
   2          5    00           0         16839648   16839647
   3          4    00     8909712      2048256   10957967
   6         14    01          0         16839648   16839647
   7         15    01    8194032         2016       8196047

 

2. Looking at the partition column reveals that partitions 4 and 5 are free

3. Determine the subdisk name with the vxprint command of the volume:

#vxprint -htg rootdg opt
Disk group: rootdg

V  NAME         USETYPE      KSTATE    STATE         LENGTH   READPOL   PREFPLEX
PL NAME         VOLUME       KSTATE    STATE         LENGTH   LAYOUT    NCOL/WID MODE
SD NAME           PLEX            DISK      DISKOFFS      LENGTH   [COL/]OFF DEVICE   MODE
SV NAME           PLEX         VOLNAME NVOLLAYR  LENGTH   [COL/]OFF AM/NM    MODE

v opt          fsgen        ENABLED  ACTIVE   5880672  ROUND      -
pl opt-01     opt           ENABLED  ACTIVE   5880672  CONCAT    -         RW
sd rootdisk-03  opt-01       rootdisk 10957967 5880672  0         c0t0d0   ENA    <-----------------------


4. rootdisk-03 is the subdisk name (subdisk=sd)

5. Add the partition ("5" in this case, along with tag "0x09" and flag "0x00") with the vxmksdpart command. Consult the man page on the prtvtoc command for more information on what the tag and flag options are

#/usr/lib/vxvm/bin/vxmksdpart -g< diskgroup> <subdisk name>  <partition  number>   <tag> <flag>

Note:  <tag> and <flag> are hexadecimal

#/usr/lib/vxvm/bin/vxmksdpart -g rootdg rootdisk-03 5 0x09 0x00

 

6. Check to see if the partition was made with the prtvtoc command:

# prtvtoc /dev/dsk/c0t0d0s2
/dev/dsk/c0t0d0s2 partition map

Dimensions:
512 bytes/sector
63 sectors/track
16 tracks/cylinder
1008 sectors/cylinder
16708 cylinders
16706 accessible cylinders

Flags:
1: unmountable
10: read-only

Unallocated space:
First     Sector    Last
Sector     Count    Sector
8192016   4286775280 4294967295
16839648 4286321680    8194031
16838640   1008           16839647

First     Sector    Last
Partition  Tag  Flags    Sector      Count       Sector   Mount Directory
    0         2     00          0          8192016    8192015
    1         3    01     8196048      713664     8909711
    2         5    00          0          16839648  16839647
    3         4    00    8909712     2048256    10957967
    5         9    00   10957968    5880672    16838639     <------ new partition for opt
    6        14   01         0          16839648    16839647
    7        15   01    8194032       2016          8196047

Upon the next reboot, the new slice should be available as long as relevant changes have been made to /etc/vfstab. Alternatively, it can be mounted without a reboot as long as the opt volume is first taken offline, i.e. the volume stopped and the file system unmounted.