Understanding VDisk and Disk Statistics

VDisk Statistics

To view the statistics for a VDisk, from "Virtual Disks", click on the "View" link under Statistics for the VDisk. A Value with a suffix GB indicates gigabytes, MB megabytes etc.

The statistics for a VDisk are incrementing counters and can be reset

The following are the statistics maintained for a VDisk

Write Size: The amount of data written to the VDisk

Write Ops: The number of write commands

Read Size: The amount of data read from the VDisk

Read Ops: The number of read commands

Unaligned Size: This the amount of write data which is not aligned on a 4K boundary.

For example a write size of 512, 1024, 4068 etc. This applies to VDisk with 512e enabled

Data Deduped: The amount of write data that has been deduplicated

Data Unmapped: The amount of unmap/discard/trim data

Unmap Ops: The number of unmap commands

Blocks Zeroed: The amount of data zeroed as a result of a block zeroing command

Uncompressed Size: The amount of data written to disk in an uncompressed form

Compressed Size: The amount of data written to disk in a compressed form

Compression Hits: The amount of data that was successfully compressed

Compression Misses: The amount of data for which an attempt to compress was unsuccessful

Verify Hits: With verification enabled, this is the amount of duplicate data for which verification was successful

Verify Misses: With verification enabled, this is the amount of duplicate data for which verification was unsucessful (Hash collisions)

Verify Errors: This records the errors during verification process if any (read errors of the previous duplicate block)

CW Hits: Atomic Test and Set commands which were successful

CW MIsses: Atomic Test and Set commands which were unsuccessful

XCopy Write: The data written to the VDisk for VAAI Full Clone / XCopy (hardware offload) commands

XCopy Read: The data read from the VDisk for VAAI Full Clone / XCopy (hardware offload) commands

XCopy Ops: The number of VAAI Full Clone / XCopy commands recevied by the VDisk

Write Same Size: The total size of zero data written as a result of VAAI Write Same / Block Zero commands

Write Same Ops: The number of VAAI Write Same / Block Zero commands received by the VDisk

Populate Token Size: (Commercial Edition) The read size of Populate Token commands (Offloaded Data Transfers / ODX)

Populate Token Ops: (Commercial Edition) The number of Populate Token commands (Offloaded Data Transfers / ODX) received by the VDisk

Write Using Token Size: (Commercial Edition) The read size of Write Using Token commands (Offloaded Data Transfers / ODX)

Write Using Token Ops: (Commercial Edition) The number of Write Using Token commands (Offloaded Data Transfers / ODX) received by the VDisk

The transfer rate statistics such as Write Transfer Rate, Read Tranfer Rate etc. have been removed. The values reported by them were incorrect.

Disk Statistics

In the case of a Disk, the recorded statistics show the amount of disk space used, the amount of duplicated data the space corresponds to etc.

The following are the recorded statistics

Total Size: Total disk space configured

Used Size: Total disk space used

VDisk Usage: Total disk space used by VDisks. This excludes metadata used for other purposes

Deduped Size: The amount of write data that has been deduplicated

Uncompressed Size: The amount of data stored in an uncompressed form

Compressed Size: The amount of data stored in a compressed form

Compression Hits: The amount of data that was successfully compressed

Dedupe Ratio: The total space savings ratio. This is calculated as below

(Deduped Size + Uncompressed Size + Compression Hits) / (Uncompressed Size + Compressed Size)