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Thursday, 4 January 2018

Add a meta device with soft partitions in Main Mirror (Solaris SVM)


Adding a meta device with soft partitions to Main Mirror in Solaris SVM.


Storage LUN (c4t60000970000297000217533030373445d0s0) is under control of metadevice d888 which is having two soft partitions d890 and d891. Customer want to mirror this LUN to another LUN from different storage. For mirroring, we need to add both the LUNs under a Main Mirror in SVM. However, the source LUN is having soft partitions so we cannot simply add this LUN under main mirror.


1.      Remove the Soft partitions from the meta device and note down the starting and ending block details.
2.      Add the Meta Device under the control of Main Mirror.
3.      Create the Soft partitions on the Main Mirror.
4.      Create Meta Device on new LUN and add it under Main Mirror.

Note: This process involves downtime because the mount points needs to be unmounted which are using the soft partitions. Before initiating with the procedure, take latest backup of these mount points.


1.      Note down the MetaDevice and soft partition details from the output of metastat –p command.

d888 1 1 c4t60000970000297000217533030373445d0s0
d891 -p d888 -o 104861504 -b 102760448
      d890 -p d888 -o 3872 -b 104857600

Here d888 is the Meta Device and d890 and d891 are the soft partitions and they are mounted on the server as below:

/dev/md/dsk/d890        49G   1.0G    48G     3%    /test1
/dev/md/dsk/d891        48G    49M    48G     1%    /test2

2.      Unmount the mount points
3.      Clear the Soft Partitions

root@test # metaclear d890
d890: Soft Partition is cleared
root@test # metaclear d891
d891: Soft Partition is cleared

4.      Add the metadevice d888 to Main Mirror d880

root@test # metainit d880 -m d888
d880: Mirror is setup

5.      Verify the Main Mirror Properties of d880

root@gnnems25 # metastat d880
d880: Mirror
            Submirror 0: d888
            State: Okay
            Pass: 1
            Read option: roundrobin (default)
            Write option: parallel (default)
            Size: 209710080 blocks (99 GB)

d888: Submirror of d880
            State: Okay
            Size: 209710080 blocks (99 GB)
            Stripe 0:
              Device                                    Start Block  Dbase        State Reloc Hot Spare
        c4t60000970000297000217533030373445d0s0          0     No            Okay   Yes

6.      Create the soft partitions on the Main Mirror referring the output of metastat –p in step 1.

root@test # metainit d891 -p d880 -o 104861504 -b 102760448
d891: Soft Partition is setup
root@test # metainit d890 -p d880 -o 3872 -b 104857600
      d890: Soft Partition is setup

7.      Mount the Soft partitions to verify the data integrity.

root@test # mount /dev/md/dsk/d890 /test1
root@test # mount /dev/md/dsk/d891 /test2

Verify the Size details in df –h, which will be same as earlier and data will be accessible.

/dev/md/dsk/d890        49G   1.0G    48G     3%    /test1
/dev/md/dsk/d891        48G    49M    48G     1%    /test2

8.      Create MetaDevice on the new LUN and add the new MetaDevice under main mirror d880  using standard procedure.

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