Tag: ESXi

Configuration Examples and Troubleshooting for VMDirectPath

TIPS

VMDirectPath allows guest operating systems to directly access an I/O device, bypassing the virtualization layer. This direct path, or passthrough can improve performance for VMware ESX™ systems that utilize
high‐speed I/O devices, such as 10 Gigabit Ethernet. The below documentation allows to configure and troubleshoot the VMDirectPath.

Source: Configuration Examples and Troubleshooting for VMDirectPath

How to check the disk performance using dd

Storage

dd command should be available in ESXi as well as all Linux versions. If you face any issues with your application and wants to know the disk performance is deteriorated, you can quickly use the dd command to check the write/read performance of the disk. The disk used can be even a datastore or a network device also. You can cross check with another system or disk where you don’t see any performance issues to compare the results to know if there is any issues with the disk.

Below is the example to run in a VMWare ESXi volume.

/vmfs/volumes/54a55c07-9face633-0999-002590fc98c8 # time dd if=/dev/zero of=test bs=1M count=1024

1024+0 records in 1024+0 records out

real 2m 7.62s user 0m 4.69s sys 0m 0.00s

= ( 1024/127 = 8 MB/s !!! )

In the above example you are trying to write a 1GB file and you are using time command to find out the speed at which the write happened.

Source: Horrible disk performance under ESXi | [H]ard|Forum

ESXTOP & Queues – VMware Technology Network VMTN

VMware

This page provides you a quick summary on what is AQLEN and DQLEN in ESXi.

AQLEN is the adaptor queue length. This should be derived from storage adaptor queue depth, which is the maximum commands which can be in the queue waiting for process.

DQLEN is the device queue length. This should be derived from storage device(usually drives) queue depth, which is the maximum commands which can be in the queue waiting for process.

 

Source: ESXTOP & Queues – VMware Technology Network VMTN