HP StorageWorks Data Replication Manager HSG80 ACS Version 8.7P Configuration Guide (AA-RPHZF-TE, March 2004)

215Data Replication Manager HSG80 ACS Version 8.7P Configuration Guide
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Replicating Storage Units
This chapter describes Data Replication Manager (DRM) concepts and procedures for making
point-in-time copies of a storage unit.
The topics discussed in this chapter are:
■ Cloning Data for Backup‚ page 217
■ Snapshot‚ page 219
Cloning and snapshot are methods of making a point-in-time copy of a storage unit. Table 24
provides an overview comparison of the two methods.
Table 24: Cloning and Snapshot Comparison
Cloning Snapshot
Can be performed at initiator site or
target site.
Can be performed at target site only.
A physical copy that resides on disk.
Can be a source for another clone.
Source and cloned units.
A virtual copy that resides on disk and
in cache.
May not be snapped or cloned.
Requires 512 MB cache for both
controllers.
Read/write capability Read/write capability
Data captured in hours (for moderate
I/O loads, possibly at a rate of 60
GB/hour).
Data captured in seconds.
Can make four at a time per 6-member
mirrorset. Limited by number of drives
and number of mirrorsets allowed at
any one time.
Four snapshot units allowed per storage
array. One per source unit at any one
time.
The source unit must have write-back
cache disabled.
The source unit must have the following
characteristics:
Less than 512 GB
Write-back cache enabled
Nontransportable
Requires ACS Version 8.7S or 8.7P