Hitachi MK-96RD626-07 - Manual (Page 56)

2-36 About Universal Volume Manager Operations
Hitachi Universal Storage Platform V/VM Universal Volume Manager User’s Guide
Copy-on-Write Snapshot Operations
Figure 2-16 shows the use of an external volume for the Copy-on-Write
Snapshot operation. The mapped external volume is set as a pool-VOL of the
Copy-on-Write Snapshot pair. For details on Copy-on-Write Snapshot, see the
Copy-on-Write Snapshot User’s Guide.
The procedure for the operation is as follows:
1. Use Universal Volume Manager to map a volume in the external storage
system as an internal volume of the local storage system.
Caution: Set the emulation type of the volume to OPEN-V when you map
the volume, because the volume with the OPEN-V emulation type can only
be set as a pool-VOL of Copy-on-Write Snapshot.
2. The status of the mapped volume automatically becomes Normal. However,
the volume formatting processing is not executed automatically. If you
need to format the mapped volume, format the volume using the VLL
function. For the volume formatting operation procedure, see the Virtual
LVI/LUN and Volume Shredder User's Guide.
3. Create a pool and add the mapped external volume to that pool as a pool-
VOL.
4. Set the P-VOL and S-VOL of the Copy-on-Write Snapshot pair with
specifying the pool you have created at the step 3.
Mapping Copy-on-Write
Snapshot
P-VOL
Creating a Copy-on-Write Snapshot pair.
Copy-on-Write
Snapshot
S-VOL
Copy-on-Write
Snapshot
Pool-VOL
As you create a Copy-on-Write Snapshot pair,
the data of the internal volume in the local storage system that is set as a
P-VOL is copied to the external volume that is set as a pool-VOL
: Virtual volume (S-VOL of the Copy-on-Write Snapshot pair)
Local Storage System External Storage System
: Internal volume
: Internal volume where the external volume is mapped
: External volume
Legend
: Data copy direction
Figure 2-16 Example of the Copy-on-Write Snapshot Operation