Dell PowerVault MD3260i - Manual (Page 332)

Parameters
Parameter Description
ssdCache The alphanumeric identifier (including - and _) of the SSD
cache for which you want to get information. Enclose the
identifier in square brackets ([ ]). If the SSD cache name
contains special characters or consists only of numbers,
you also must enclose the identifier in double quotation
marks (" ") inside square brackets.
RAID controller module Each RAID controller module stores SSD cache metadata
for the virtual disks that it owns. Therefore, the SSD cache
statistics are maintained and displayed per RAID
controller module. Valid RAID controller module identifiers
are 0, 1, or both, where 0 is the RAID controller module in
slot 0, 1 is the RAID controller module in slot 1, and both is
both RAID controller modules. Enclose the RAID controller
module identifier in square brackets ([ ]). If you do not
specify a RAID controller module, the default value is
both.
file The file path and the file name to which you want to save
the SSD cache statistics. Additional statistics are
available when you save the statistics to a file.
Enclose the file name in double quotation marks (" "). For
example: file="C:\Program Files\CLI\logs \statistics.csv".
Notes
The following statistics are displayed on the screen:
Reads Total number of host reads of SSD cache-enabled virtual disks.
Compare the Reads relative to Writes. The Reads need to be greater than the Writes for
effective SSD cache operation. The greater the ratio of Reads to Writes the better the
operation of the cache.
Writes Total number of host writes to SSD cache-enabled virtual disks.
Cache Hits A count of the number of cache hits.
Cache Hits (%) Derived from Cache Hits/total reads.
The Cache Hit percentage should be greater than 50% for effective SSD cache operation. A
small number could be indicative of several things:
• Ratio of Reads to Writes is too small
• Reads are not repeated
• Cache capacity is too small
NOTE: To help determine the ideal SSD cache capacity, you can run the Performance
Modeling Tool using the start ssdCache [ssdCacheName]
performanceModeling command.
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