My top performances counters to messure Windows Logical Disk performance.
These are some of the explanations that I have been able to extract from Microsoft and other web pages. The interpretations of the counters could vary according to parameters or configurations that each one can have.
[ ] Performance Counters
[
] LogicalDisk
[ ] Avg. Disk sec/Read
Counter:
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LogicalDisk - Avg. Disk sec/Read
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Description
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Avg. Disk sec/Read is the average
time, in seconds, of a read of data from the disk.
Measure latency directly at the
layer just above where the storage device drivers hook into the operating
system. These help to accurately measure how long the drivers and hardware
took to service an I/O request no matter what kind of hardware you have.
|
Options
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Total or Disk values
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Threshold /
Values
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Measures read latency on the
disks. ( < .005 excellent; .005 – .010 Good; .010 – .015 Fair; > .015
investigate)
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Units
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seconds
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How to interpret the value
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[
] Avg. Disk sec/Write
Counter:
|
LogicalDisk - Avg. Disk sec/Write
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Description
|
Avg. Disk sec/Write is the
average time, in seconds, of a write of data to the disk.
Measure latency directly at the
layer just above where the storage device drivers hook into the operating
system. These help to accurately measure how long the drivers and hardware
took to service an I/O request no matter what kind of hardware you have.
|
Options
|
Total or Disk values
|
Threshold /
Values
|
Measures write latency on the
disks. ( < .005 excellent; .005 – .010 Good; .010 – .015 Fair; > .015
investigate)
|
Units
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seconds
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How to interpret the value
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[
] Disk Read/sec
Counter:
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LogicalDisk - Disk Read/sec
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Description
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Disk Reads/sec is the rate of
read operations on the disk. Number of read IOPs.
|
Options
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Total or Disk values
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Threshold /
Values
|
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Units
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seconds
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How to interpret the value
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[
] Disk Write/sec
Counter:
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LogicalDisk - Disk Write/sec
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Description
|
Disk Writes/sec is the rate of
write operations on the disk. Number of write IOPs.
|
Options
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Total or Disk values
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Threshold / Values
|
|
Units
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seconds
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How to interpret the value
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[
] Average Disk Queue Length
Counter:
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LogicalDisk - Average Disk Queue Length
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Description
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Avg. Disk Queue Length is the
average number of both read and write requests that were queued for the
selected disk during the sample interval.
Avg. Disk Queue Length (Avg.
Disks Read Queue Length, Avg. Disk Write Queue Length)
Avg. Disk Queue Length is equal
to the (Disk Transfers/sec) *( Disk sec/Transfer) , which is the average
response of the device times the I/O rate. As you would expect, the Avg. Disk
Read Queue Length is equal to the “(Disk Reads/sec) * (Disk sec/Read)” and
Avg. Disk Write Queue Length is equal to the “(Disk Writes/sec) * (Disk
sec/Write)”.
Counter can reveal whether the
drive is keeping up with the demand of running processes. The most frequently
cited threshold is two items in the queue. If the average is greater than 2,
a drive bottleneck might be occurring. This counter should also be compared
with the baseline. If the baseline shows an average of 2.3 items in the disk
queue and performance was perceived as acceptable, there’s no reason to
suggest that performance is unacceptable—at a later time—if the average is
the same or lower. Remember, performance is measurable with statistics, but
whether performance is “good” or “bad” is a relative issue.
The Avg. Disk Queue Length
counter is derived from the product of Avg. Disk sec/Transfer multiplied by
Disk Transfers/sec.
For example, the Avg. Disk Queue
Length counter reads 10.3, and the Current Disk Queue Length counter shows
four requests in the disk queue at the end of the measurement interval. If
the previous value of Current Disk Queue Length was 0, the equilibrium
assumption necessary for Little's Law does not hold. Since the number of
arrivals is evidently greater than the number of completions during the
interval, there is no valid interpretation for the value in the Avg. Disk
Queue Length counter, and you should ignore the counter value. However, if
both the present measurement of the Current Disk Queue Length counter and the
previous value are equal, then it is safe to interpret the Avg. Disk Queue
Length counter as the average number of outstanding I/O requests to the disk
over the interval, including both requests currently in service and requests
queued for service.
|
Options
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Total or Disk values
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Threshold / Values
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1 < Good / 3<=Fair (base on baseline)
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Units
|
|
How to interpret the value
|
Counter can reveal whether the
drive is keeping up with the demand of running processes. The most frequently
cited threshold is two items in the queue. If the average is greater than 2,
a drive bottleneck might be occurring. This counter should also be compared
with the baseline. If the baseline shows an average of 2.3 items in the disk
queue and performance was perceived as acceptable, there’s no reason to
suggest that performance is unacceptable—at a later time—if the average is
the same or lower. Remember, performance is measurable with statistics, but
whether performance is “good” or “bad” is a relative issue.
Be careful when using old
thresholds of 2 with SQL Server and SANs.
This value can be much higher than 2.
Do not rely solely on this counter to diagnose an IO problem.
Possible HD problems.
|
[
] Disk Bytes/sec
Counter:
|
LogicalDisk - Disk Bytes/sec
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Description
|
Disk Bytes/sec is the rate bytes
are transferred to or from the disk during write or read operations.
Perfmon captures the total number
of bytes sent to the disk (write) and retrieved from the disk (read) over a
period of one second. If the Perfmon capture interval is set for anything
greater than one second, the average of the values captured is presented.
The Disk Read Bytes/sec and the
Disk Write Bytes/sec counters break down the results displaying only read
bytes or only write bytes, respectively.
|
Options
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Total or Disk values
|
Threshold / Values
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Good < 1. High values are Good
if this value is low could have problems.
|
Units
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Seconds
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How to interpret the value
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Can reveal whether the drive is
living up to expectations. Many drives are rated at a certain speed, but they
perform at lower speeds. This counter can reveal such behavior. In many
cases, updating drive controller drivers might resolve such performance
problems.
|
[
] Disk Transfers/sec
Counter:
|
LogicalDisk - Disk Transfers/sec
|
Description
|
Disk Transfers/sec is the rate of
read and write operations on the disk.
Perfmon captures the total number
of individual disk IO requests completed over a period of one second. If the
Perfmon capture interval is set for anything greater than one second, the
average of the values captured is presented.
Disk Reads/sec and Disk Writes/sec
are calculated in the same way, but break down the results in read requests
only or write requests only, respectively.
|
Options
|
Total or Disk values
|
Threshold / Values
|
Good < 1. High values are Good
if this value is low could have problems.
|
Units
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Seconds
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How to interpret the value
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Number of read and write IOPs
(used to compare against capacity of storage subsystem)
|
[
] Split IO/Sec
Counter:
|
LogicalDisk - Split IO/Sec
|
Description
|
Split IO/Sec reports the rate at
which I/Os to the disk were split into multiple I/Os. A split I/O may result
from requesting data of a size that is too large to fit into a single I/O or
that the disk is fragmented.
Measures the rate of IO split due
to file fragmentation. This happens if the IO request touches data on
non-contiguous file segments.
|
Options
|
Total or Disk values
|
Threshold / Values
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High values are Bad, there are a
lot of fragmentation.
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Units
|
|
How to interpret the value
|
Measures the rate of IO split due
to file fragmentation. This happens if the IO request touches data on
non-contiguous file segments.
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[ ] Tools
https://gallery.technet.microsoft.com/DiskSpd-a-robust-storage-6cd2f223
https://gallery.technet.microsoft.com/DiskSpd-a-robust-storage-6cd2f223
[ ] More Information
by GoN | Published: December 17, 2016 | Last Updated: Febrary 16, 2017
