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Chapter 7: VSP G1x00 and F1x00 batteries
The batteries temporarily provide the storage system with power to maintain its caching
operation during a power failure event. The following information describes the battery
life expectancy, battery operation, and cache backup process. Also, some specific
guidelines are provided for storing the system during an extended period of time non-
operation.
Battery backup operations
The storage system is designed to retain data and configuration information when the
power fails. The battery system can provide sufficient power with fully charged batteries
to completely back up all data in the cache if two consecutive power failures occur. If the
batteries do not contain enough charge to provide sufficient time to back up the cache
when a power failure occurs, the cache operates in write-through mode and writes
directly to the drives to prevent slow data throughput via the cache. When the battery
charge is 50% or more, the cache write through mode is turned off and the system
operates normally.
If a power failure occurs and continues for up to 20 milliseconds, the storage system
continues normal operation. If the power failure exceeds 20 milliseconds, the storage
system uses power from the batteries to keep the cache active while the system copies
the storage system configuration and cached data to the cache flash memory in the
cache backup modules. The process continues up to 32 minutes. The cache flash drives
do not require power to retain the data.
The following illustration shows the timing if a power failure occurs.
Item
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Hitachi Virtual Storage Platform G1000, G1500, and VSP F1500 Hardware Guide
Power failure occurs.
Chapter 7: VSP G1x00 and F1x00 batteries
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