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Troubleshooting vSphere Storage

You're reading from   Troubleshooting vSphere Storage All vSphere administrators will benefit big-time from this book because it gives you clear, practical instructions on troubleshooting a whole host of storage problems. From fundamental to advanced techniques, it's all here.

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Product type Paperback
Published in Nov 2013
Publisher Packt
ISBN-13 9781782172062
Length 150 pages
Edition 1st Edition
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Mike Preston Mike Preston
Author Profile Icon Mike Preston
Mike Preston
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Toc

esxtop statistics


esxtop collects an abundance of statistics regarding all aspects of how your ESXi host and VMs are performing. Although it is possible to view metrics in regards to CPU, memory, and networking as well, I've only outlined the storage-related metrics here. The thresholds listed here are simply suggested values, thresholds that I've seen used in many whitepapers, VMware documentation, and resources in the past. There are many different reasons why a threshold could be met, so these are certainly not hard numbers.

Have a look at the following table:

Statistic

Description

Threshold

CMDS/s

Number of commands issued per second.

varies

READS/s

Number of read commands issued per second.

varies

WRITES/s

Number of write commands issued per second.

varies

MBREAD/s

Megabytes read per second.

varies

MBWRTN/s

Megabytes written per second.

varies

DAVG/cmd

Latency observed by the device driver—roundtrip latency from HBA to storage array. Sustained thresholds usually indicate a performance issue with the underlying storage.

25

KAVG/cmd

Latency observed inside the VMkernel. Value should always be very low if not 0 unless queuing is observed.

1

QAVG/cmd

Latency observed inside the queue. This is part of KAVG/cmd. Sustained values indicate an issue with queuing or queue depth.

1

GAVG/cmd

Round trip latency as observed by the guest OS. Normally a total of DAVG, KAVG, and QAVG.

25

AQLEN

The storage adapter queue length—maximum number of active commands the adapter is configured for.

n/a

LQLEN

The LUN queue depth—maximum number of active commands the LUN can have.

n/a

WQLEN

The world queue depth—maximum number of active commands the world can contain.

n/a

ACTV

The number of commands that are currently active within the VMkernel.

varies

QUED

The number of commands that are currently queued in the VMkernel waiting for processing. Sustained thresholds may indicate a need to increase queue depth or an issue with the underlying storage array.

1

%USD

The percentage of queue depth used by active commands. Normally sits close to 0 unless queuing is occurring.

1

LOAD

The total number of active and queued commands as compared to queue depth. Should always be 0 unless queuing is occurring.

1

ABRTS/s

The number of commands that have been aborted per second. Normally indicates that the underlying storage is unable to meet the demands of your workloads.

1

RESETS/s

The number of commands reset per second.

1

RESV/s

The number of SCSI reservations issued per second.

n/a

CONS/s

The number of SCSI reservations conflicts occurring per second. Sustained high values could indicate that actions need to be taken to balance the metadata heavy operations.

20

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