Item Description Item Description
1 and 2 Cluster 1 3 and 4 Cluster 0
Memory operation
The controller places all read and write data into the cache. The amount of fast-write
data in cache is dynamically managed by the cache control algorithms to provide an
optimum amount of read and write cache, depending on the workload read and write
I/O characteristics.
Data protection
The VSP G1000, VSP G1500, and VSP F1500 storage systems protect the loss of data or
conguration information stored in the cache when electrical power fails. The cache is
k
ept active for up to 32 minutes b
y the cache backup batteries while the system
conguration and data ar
e copied to the cache ash memory in the cache backup
modules. For mor
e information, see
Cache ash memory (on page 58) and Battery
backup operations (on page 125) .
Cache capacity
The r
ecommended amount of cache to install is determined b
y the RAID le
vel, the
number of drives installed in the system, and whether
Hitachi Dynamic Provisioning
(HDP), Hitachi Dynamic Tiering (HDT), Dynamic Cache Residency (DCR), and Universal
Volume Manager (UVM) are applied. The recommended data cache capacity per Cache
Logical Partition (CLPR) = (CLPR capacity) - (DCR Extent setting capacity per CLPR). When
CLPR is not applied to DP/DT/DCR, install the recommended data cache capacity shown
in the following table.
To congure a system for maximum performance, contact your authorized Hitachi
Vantara representative. See Getting Help in the preface of this manual.
Table 12 Recommended data cache capacity when DP, DT, DCR, and UVM are not
being used
Total logical capacity of external volumes
+ internal volumes per CLPR
Recommended data cache capacity per
CLPR
Less than 2,900 GB 15 GB or more
Less than 2,900 GB 15 GB or more
2,900 GB or more 16 GB or more
11,500 GB or more 22 GB or more
14,400 GB or more 24 GB or more
Memory operation
Chapter 2: Storage system hardware overview
Hitachi Virtual Storage Platform G1000, G1500, and VSP F1500 Hardware Guide 53
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