NEC NF2900-SR40E, Руководство пользователя

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13. Snap Shot
The snap shot function can instantaneously make a virtual copy of a logical disk in the same disk array
unit. Only the difference data between the copy source and the virtual copy is managed, so copies can
be of a small size.
The following specific software (available optionally) is necessary for using the Snap Fhot feature.
NEC Storage S2500/S1500 contains the Dynamic Data Replication and Snap Shot as paired package.
For details on the usage, refer to the User's Guide provided with the software.
Before the feature can be used on this disk array unit, the license lock must be released by using the
license key provided with the software.
You can release the license lock and make setting changes by yourself.
An NEC maintenance service representative may provide the installation service (at an additional
charge) for releasing the license lock and changing settings. Contact your maintenance service
representative if necessary.
13.1 Note on Using Snap Shot
SnapShot manages the difference data between the logical disk as the copy source and the virtual copy,
as a map in the cache memory. Thus, if the disk array unit is turned OFF and the time limit for holding
data by batteries is exceeded, processing for creating the management information of the difference
data is performed upon the next system start. As a result, the system startup is delayed depending on
the difference data held by Snap Shot. (Delay time: About 10 minutes per 1TB of difference data )
So, to avoid the huge delay at next system startup with fully a discharged battery, please begin the
shutdown process by pushing the Shutdown button before the power to the disk array unit is turned
OFF. As the management information of the difference data will be stored on hard disk by proper
execution of shutdown process, the delay of the next system startup with fully discharged battery will
be reduced considerably.