hit blocks, it is possible that a different I/O characteristic type (file system, database,

 

or web server) could improve the performance.

Misses

Number of host reads where none of the blocks were in the SSD cache. This is an

 

SSD cache miss where the reads were satisfied from the base virtual disk.

Misses - Blocks

Number of blocks in Misses.

Populate

Number of host reads where data was copied from the base virtual.

Actions (Host

 

Reads)

 

Populate

Number of blocks in Populate Actions (Host Reads).

Actions (Host

 

Reads) - Blocks

 

Populate

Number of host writes where data was copied from the base virtual disk to the SSD

Actions (Host

cache.

Writes)

The Populate Actions (Host Writes) count may be zero for the cache configuration

 

settings that do not fill the cache as a result of a Write I/O operation.

Populate

Number of blocks in Populate Actions (Host Writes).

Actions (Host

 

Writes) - Blocks

 

Invalidate

Number of times data was invalidated/removed from the SSD cache. A cache

Actions

invalidate operation is performed for every host write request, every host read

 

request with Forced Unit Access (FUA), every verify request, and in some other

 

circumstances.

Recycle

Number of times that the SSD cache block has been reused for another base virtual

Actions

disk and/or a different LBA range.

 

For effective cache operation, it is important that the number of recycles is small

 

compared to the combined number of read and write operations. If the number of

 

Recycle Actions is close to the combined number of Reads and Writes, then the

 

SSD cache is thrashing. Either the cache capacity needs to be increased or the

 

workload is not favorable for use with SSD cache.

Available Bytes

Number of bytes available in the SSD cache for use by this RAID controller module.

 

The available bytes, allocated bytes, and user data bytes are used to compute the

 

Cache Allocation % and the Cache Utilization %.

Allocated Bytes

Number of bytes allocated from the SSD cache by this RAID controller module.

 

Bytes allocated from the SSD cache may be empty or they may contain data from

 

base virtual disks.

 

The available bytes, allocated bytes, and user data bytes are used to compute the

 

Cache Allocation % and the Cache Utilization %.

User Data Bytes

Number of allocated bytes in the SSD cache that contain data from base virtual

 

disks.

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