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(5) Selection of Cache Memory
Minimum capacity of cache memory per node is 8GB and the performance of disk array unit
improves by adding the cache memory. You can expand the cache memory from 8GB to 16GB and 32GB.
8GB cache memory consists of 2 cache memory modules, and 8GB or more cache memory consists of 4
cache memory modules.
In case the cache memory module is configured with 2 modules, it operates as a duplicated cache, and
in the event of the failure of cache memory module, Write Cache operation changes to Write through
like conventional mid-sized machine, and Write performance significantly deteriorates. However, in
case of the cache memory modules are configure by 4 modules, they operate as two pairs of duplicated
cache and in the event of the failure of cache memory module, as redundancy is
kept by the other pair, Write Cache operation can continue. Therefore, you can minimize the
performance deterioration.this unit.
By adding cache, due to the effect of cache hit, you can improve Read/Write performance of the unit.
According to the performance cache hit you expect, you need to add the cache memory but in general,
mount the cache in proportion to the disk capacity you mount into the unit. The followings are
our recommendable figures to mount cache for disk capacity:
Meanwhile, the cache memory works as the disk cache of the disk drives of the mounted node.
In addition, in case of multiple nodes, you can expand the capacity individually.
Target of cache capacity per node
Logical disk
capacity
(GB)
Cache capacity
(GB)
- 4,000
8GB
4,001 - 8,000 16GB
8,001 -
32GB
Product model
number
Product name
Product outline
NF5183-SC21E Extended cache module
(CHE) (8GB)
For NF5183-SB401E
Extended node chassis (NF5183-SB03E)
Cache memory 8GB: (4GB/module)x2
+ Battery backup unit x2 (for 2 modules)
NF5183-SC22E Extended cache module
(CHE) (16GB
Æ
32GB)
For NF5183-SB401E
Extended node chassis (NF5183-SB03E)
Additional cache memory from 16GB to 32GB
# Logical disk capacity is user’s capacity of Disk
Array Unit.
(Example: capacity equivalent to “D” configured by
RAID-5(4D+P) )
Beside, the left column is the minimum requirement,
mere target and we recommend to mount as much as
possible.
