Storage System Information Retention Function - NEC M310 Configuration Manual

5. Functions <Storage System Information Retention Function>

Storage System Information Retention Function

When using the data replication function, the storage system data such as the differential map between
the master volume (MV) and the replication volumes (RV) is created in the cache memory. The storage
system information retention function backs up the storage system data to a disk drive. The volume to
backup, which is called "replication reserved volume", can be configured by the procedures in the NEC
StorageManager manual.
It is strongly recommended to use the storage system information retention function when using data
replication function. When not using the storage system information retention function, the updated
difference data is not saved when rebooting after the scheduled plan is completed, and requires a full
copy of data in MV to RV. Until copying of the entire data completes, an I/O load occurs which affects
the performance of operation. The replication reserved volume is 8.6GB (1GB=1000
(1G=1024 3 Byte).
Note:
Storage system information retention function is used for the planned stoppage to restore the storage
system information during the shutdown procedure but will not work for a power outage.
1. Replication Reserved Volume
Shutdown
Difference
ＭＶ
Manage differential
map of data
Replication
Reserved
Volume
Only the difference
is copied from MV
ＲＶ
to RV at reboot
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2. No Replication Reserved Volume
Shutdown
No differential
map of data
Difference
ＭＶ
3 Byte) / 8.0GB
Full copy of MV
to RV at rebootà
ＲＶ
Increase I/O load
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