Installation guide

Table C-3. Disk Data Counters (Continued)
Counter Label Description
Entity
V H R C
kernelWriteLatency Kernel Disk Write
Latency
Average amount of time, in milliseconds, spent by VMKernel
processing each SCSI write command.
n
Stats Type: absolute
n
Unit: millisecond
n
Rollup Type: average
n
Collection Level: 2
n
VC/ESX: Yes/Yes
o • ο ο
maxTotalLatency Highest Disk
Latency
Highest latency value across all disks used by the host. Latency
measures the time taken to process a SCSI command issued by
the guest OS to the virtual machine. The kernel latency is the
time VMkernel takes to process an IO request. The device
latency is the time it takes the hardware to handle the request.
Total latency = kernelLatency + deviceLatency
n
Stats Type: absolute
n
Unit: millisecond
n
Rollup Type: average
n
Collection Level: 1
n
VC/ESX: Yes/Yes
ο • ο ο
numberRead Disk Read
Requests
VM
Number of times data was read from each
virtual disk on the virtual machine.
Host
Number of times data was read from each
LUN on the host during the collection
interval.
n
Stats Type: delta
n
Unit: number
n
Rollup Type: summation
n
Collection Level: 3
n
VC/ESX: Yes/Yes
• • ο ο
numberWrite Disk Write
Requests
VM
Number of times data was written to each
virtual disk on the virtual machine.
Host
Number of times data was written to each
LUN on the host during the collection
interval.
n
Stats Type: delta
n
Unit: number
n
Rollup Type: summation
n
Collection Level: 3
n
VC/ESX: Yes/Yes
• • ο ο
queueLatency Queue Command
Latency
Average amount of time spent in the VMkernel queue, per SCSI
command, during the collection interval.
n
Stats Type: absolute
n
Unit: millisecond
n
Rollup Type: average
n
Collection Level: 2
n
VC/ESX: Yes/Yes
o • ο ο
Appendix C Performance Metrics
VMware, Inc. 339