Perforcache - NEC M310 Configuration Manual

5. Functions <PerforCache (1)>

PerforCache

PerforCache function improves disk array response by using SSDs (Solid State Drive) as second
cache. It reduces HDD (Hard Disk Drive) access associated with cache miss. The advantages to use
this function are:
• Response performance improvement
Even when cache miss occurs due to temporary high load, access will succeed to second cache.
This prevents performance response impairment that is caused by HDD access.
• Operation cost reduction
It is possible to improve performance by using SSDs while reducing electricity consumption
substantially over standard HDDs.
PerforCache Features
Second cache is used for the following purposes:
• Read Cache
Store frequently accessed data in second cache. Provide data from second cache rather than from
HDDs when the same data is requested to be read.
• Write Cache
Improve write request response time. When there are many write requests at the same time, move
data from cache modules to second cache instead of writing data on cache modules to HDDs.
• Persistent Write
When controller is degraded, normally it will default to write-through mode to ensure data integrity.
As a result write request response will decline. Using second cache as replacement of cache in a
degraded controller prevents write request response degradation.
Business Servers
write read
Controller
Cache
Logical Disks
NEC Confidential
write read
Controller
Cache
2 Cache
nd
Pool
Disk Array
Cache
Module
SSD
HDD HDD HDD
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