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2. Basic Functions
Backup (Advanced Copy)
Backup
Local Copy
The Advanced Copy functions offer the following copy methods: "Mirror Suspend", "Background Copy", and "Copy-
on-Write". The function names that are given to each method are as follows: "EC" for the "Mirror Suspend"
method, "OPC" for the "Background Copy" method, and "SnapOPC" for the "Copy-on-Write" method.
When a physical copy is performed for the same area after the initial copy, OPC offers "QuickOPC", which only
performs a physical copy of the data that has been updated from the previous version. The SnapOPC+ function
only copies data that is to be updated and performs generation management of the copy source volume.
●
OPC
All of the data in a volume at a specific point in time is copied to another volume in the ETERNUS AF.
OPC is suitable for the following usages:
Performing a backup
•
•
Performing system test data replication
Restoring backup data (restoration after replacing a drive when the copy source drive has failed)
•
●
QuickOPC
QuickOPC copies all data as initial copy in the same way as OPC. After all of the data is copied, only updated
data (differential data) is copied. QuickOPC is suitable for the following usages:
•
Creating a backup of the data that is updated in small amounts
•
Performing system test data replication
Restoration from a backup
•
●
SnapOPC / SnapOPC+
As updates occur in the source data, SnapOPC/SnapOPC+ saves the data prior to change to the copy
destination (SDV/TPV/FTV). The data is physically stored in the SDP/TPP/FTRP prior to changes in the updated
area.
Create an SDPV as an expansion SDV area when performing SnapOPC/SnapOPC+ by specifying an SDV as the
copy destination. SDPVs are managed as volumes that configure a Snap Data Pool (SDP). Only one SDP is
configured in the ETERNUS AF.
SnapOPC/SnapOPC+ is suitable for the following usages:
•
Performing temporary backup for tape backup
Performing a backup of the data that is updated in small amounts (generation management is available
•
for SnapOPC+)
•
SnapOPC/SnapOPC+ operations that use an SDV/TPV/FTV as the copy destination logical volume have the
following characteristics. Check the characteristics of each volume type before selecting the volume type.
Table 38
Volume
Item to compare
Ease of operation
settings
Usage efficiency of the
pool
Characteristics of SnapOPC/SnapOPC+ Operations with Each Type of Copy Destination Logical
SDV
The operation setting is complex because a
dedicated SDV and SDP must be set
The usage efficiency of the pool is higher
because the allocated size of the physical
area is small (8KB)
TPV/FTV
The operation setting is easy because a dedicated SDV
and SDP are not required
The usage efficiency of the pool is lower because the
allocated size of the physical area is large with a chunk
size of 21MB / 42MB / 84MB / 168MB / 336MB
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Design Guide
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