# Counters for Disk Performance

The following table shows the name, collection level, categories, and values for counters that measure disk performance.

The VirtualCenter statistics level is a setting that controls reporting of metrics. Higher settings increase the amount of data collected and can impact performance.

- Level 1 collects resource use averages (but not for devices), uptime, heartbeat, and data for DRS (Distributed Resource Scheduler).
- Level 2 also includes usage summation and rollup types for the items above.
- Level 3 also collects device metrics in all the categories above.
- Level 4 also includes maximum and minimum rollup types.

Counter names in orange appear in the VI Client or other GUI.

### GROUP NAME: disk

Counter Name | VC Stats Level | Attribute | Value
--- | --- | --- | ---
usage Disk Usage | avg: 1 min: 4 max: 4 | description | Total amount of data read and written for all disk instances of the host or virtual machine.
unit | KB
stat type | rate
rollup type | average, minimum, maximum
entity | host and virtual machine (aggregate level only)
read Disk Read Rate | 3 | description | Amount of data read from disk during the performance interval.
unit | KBps
stat type | rate
rollup type | average
entity | host and virtual machine (per disk instance only)
write Disk Write Rate | 3 | description | Amount of data written to disk during the performance interval.
unit | KBps
stat type | rate
rollup type | average
entity | host and virtual machine (per disk instance only)
numberRead Disk Read Requests | 3 | description | Number of times data was read from disk during the performance interval.
unit | number
stat type | delta
rollup type | summation
entity | host and virtual machine (per disk instance only)
numberWrite Disk Write Requests | 3 | description | Number of times data was written to disk during the performance interval.
unit | number
stat type | delta
rollup type | summation
entity | host and virtual machine (per disk instance only)
commands Disk Commands Issued | 3 | description | Number of disk commands issued during the performance interval.
unit | number
stat type | delta
rollup type | summation
entity | host and virtual machine (per disk instance only)
commandsAborted Disk Command Aborts | 3 | description | Number of disk commands aborted during the performance interval.
unit | number
stat type | delta
rollup type | summation
entity | host and virtual machine (per disk instance only)
busResets Disk Bus Resets | 3 | description | Number of bus resets during the performance interval.
unit | number
stat type | delta
rollup type | summation
entity | host and virtual machine (per disk instance only)
totalReadLatency Disk Read Latency | 3 | description | Average time taken for a read by a Guest OS, the sum of kernelReadLatency and physical deviceReadLatency.
unit | milliseconds
stat type | absolute
rollup type | average
entity | host and virtual machine (per disk instance only)
kernelReadLatency Kernel Disk Read Latency | 3 | description | Average time spent in the ESX Server VMkernel per read.
unit | milliseconds
stat type | absolute
rollup type | average
entity | host and virtual machine (per disk instance only)
deviceReadLatency Physical Device Read Latency | 3 | description | Average time taken to complete a read from the physical device.
unit | milliseconds
stat type | absolute
rollup type | average
entity | host and virtual machine (per disk instance only)
queueReadLatency Queue Read Latency | 3 | description | Average time spent in the ESX Server VMkernel queue per read.
unit | milliseconds
stat type | absolute
rollup type | average
entity | host and virtual machine (per disk instance only)
totalWriteLatency Disk Write Latency | 3 | description | Average time taken for a write by a Guest OS, the sum of kernelWriteLatency and physical deviceWriteLatency.
unit | milliseconds
stat type | absolute
rollup type | average
entity | host and virtual machine (per disk instance only)
kernelWriteLatency Kernel Disk Write Latency | 3 | description | Average time spent in the ESX Server VMkernel per write.
unit | milliseconds
stat type | absolute
rollup type | average
entity | host and virtual machine (per disk instance only)
deviceWriteLatency Physical Device Write Latency | 3 | description | Average time taken to complete a write from the physical device.
unit | milliseconds
stat type | absolute
rollup type | average
entity | host and virtual machine (per disk instance only)
queueWriteLatency Queue Write Latency | 3 | description | Average time spent in the ESX Server VMkernel queue per write.
unit | milliseconds
stat type | absolute
rollup type | average
entity | host and virtual machine (per disk instance only)
totalLatency Disk Command Latency | 3 | description | Average time taken for disk commands by a Guest OS, the sum of kernelCommandLatency and physical deviceCommandLatency.
unit | milliseconds
stat type | absolute
rollup type | average
entity | host and virtual machine (per disk instance only)
kernelLatency Kernel Disk Command Latency | 3 | description | Average time spent in the ESX Server VMkernel per command.
unit | milliseconds
stat type | absolute
rollup type | average
entity | host and virtual machine (per disk instance only)
deviceLatency Physical Device Command Latency | 3 | description | Average time taken to complete a command from the physical device.
unit | milliseconds
stat type | absolute
rollup type | average
entity | host and virtual machine (per disk instance only)
queueLatency Queue Command Latency | 3 | description | Average time spent in the ESX Server VMkernel queue per command.
unit | milliseconds
stat type | absolute
rollup type | average
entity | host and virtual machine (per disk instance only)