Queue Depth

[Jusin_Kase]

Hello,

With the following command "esxcfg-module -s lpfc0_lun_queue_depth=16 lpfcdd_7xx" can someone tell me what 16 is, in term of unit ?

Thank you

Dominic

[mike_laspina · Accepted solution]

Hello,

Is this what your are looking for.

1. The number of outstanding SCSI commands going to a shared LUN

SCSI allows multiple commands to be active on a link, and SCSI drivers support a configurable parameter called "queue depth" to control this. The maximum supported value is most commonly 256. For an I/O group (ESX Server(s) - LUN), it is important that the number of active SCSI commands does not exceed this value, otherwise the commands will get queued. Excessive queuing leads to increased latencies and potentially a drop in throughput. The number of commands queued per ESX Server host can be derived using the esxtop command.

[Jusin_Kase]

Hello,

I am trying to make a correlation between the lpfc_lun_queue_depth Emulex driver option and AQLEN, LQLEN and others from esxtop.

For example AQLEN vmhba3 is 2038 and LQLEN is 0.

In fact when using lpfc_lun_queue_depth =16 what changes occur in esxtop ???

Thank you

Dominic

[bobross]

Check out

Appendix is a chapter on exstop. What you are changing with the command you reference is the per-LUN queue depth for that particular adapter.