Data Replication Manager(DRM) from HP

Snapshot

Snapshot creates a temporary unit to store original data that has been overwritten on the source. It does not copy all the data, unchanged data is read from the source. Snapshot requires that both controllers have 512MB of mirrored cache. The resultant Snapshot Unit is read only. Up to 4 snapshot units can be created per Source Unit.
The snapshot command is

  ADD SNAPSHOT-UNITS snapshot-unit storageset source-unit

• Source Unit is the unit name where the original data exists, and must be less than 512GB
• Snapshot Unit is a user supplied name for the copy data
• Storageset is the unassigned capacity that will be used for the Snapshot Unit. The capacity of the storageset must be equal to, or greater than the capacity of the Source Unit

Clone

The clone utility creates a complete copy of the data internally, and can copy at up to 60GB/hour if the IO load on the box is not excessive. There is no limit, beyond device capacity, to the number of clones that can be created. Once the clone command completes, it splits the two copies so they can be accessed independently. The copy point-in-time is the end of the clone process, not the time the command was issued.

Cloning is an interactive process, a typical dialogue, with user input in bold type would be

 Run Clone
 Clone local program invoked
 Units available for cloning:
  34 
 Enter unit to clone ?”  34
 clone will create a new unit which is a copy of unit 34
 enter the unit number which you want assigned to the new unit ? 42
 The new unit will be added with one of the following methods:
 1. Clone will pause after all members have been copied. The user
      must then press return to cause the new unit to be added.
 2. After all members have been copied, the unit will be added 
  automatically
  Under which above method should the new unit be added [] ? 1
 Devices available for clone targets
  Disk20300 (size=832317)
  Disk20500 (size=832317)
  Disk30300 (size=832317)
 Use available device disk20300(size=832317) for member 
  Disk10200(size=832317) (Y,N) [Y] ? Y
  Mirror disk10200 C-MA
 SET C-MA NOPOLICY
 SET C-MA MEMBERS=2
 SET C-MA REPLACE=DISK20300
 Devices available for clone targets
  Disk20500 (size=832317)
  Disk30300 (size=832317)
 Use available device disk10300(size=832317)for member 
  disk(size=832317)(Y,N)[Y] ? Y
  Mirror disk100000 C-MB
 SET C-MB NOPOLICY
 SET C-MB MEMBERS=2
 SET C-MB REPLACE=DISK10300
 Copy in progress for each new member, please be patient..
 .
 .
 copy from disk 10200 to disk20300 is 100% complete
 copy from disk 10000 to disk10300 is 100% complete
 press return when you want the new unit to be created 
 .. some mirrorset messages ..
 D44 has been created, it is a clone of D32
 Clone- normal termination

Snapclone

Snapclone is only available on the newer EVA subsystem. The snap data is available almost immediately even while clone is being built. The data copy starts out as a Snapshot and becomes a Clone once the data copy is complete.

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