ESXi hosts utilizing vmw-ahci driver may experience performance problems

Products

• VMware vSphere ESXi

Issue/Introduction

This article address performance issues being seen with generic AHCI drivers provided by ESXi in-box drivers for AHCI controllers/HBAs (Host Bus adapters) with ESXi 6.5GA (build 4564106).

Symptoms:

• Non-optimal performance of generic AHCI based storage on ESXi 6.5 GA.
• In the /var/log/vmkernel.log file of the affected ESXi host, you see entries similar to:
  
  nmp_ThrottleLogForDevice:XXXX: Cmd 0x2a (0x000000000000, xxxxx) to dev "DEVICE" on path "vmhba0:CX:TX:LX" Failed: H:0x2 D:0x0 P:0x0 Invalid sense
   
• In the /var/log/vmkernel.log file of the affected ESXi host, you see entries similar to:
  
  ScsiDeviceIO: xxxx: Cmd(0xxxxxxxxxxxx) 0x2a, CmdSN 0xxxxxxx from world xxx to dev "t10.ATA_____xxxxxxxxxxxxxxxxxxxxxxx____________________xxxxxxxxxxxxxxxxxxxxxxxx__" failed H:0x2 D:0x0 P:0x0 Invalid sense data: 0x0 0x0 0x0.
  
  Notes:
  • Vendor hardware / CPU / Sense Data may vary.
  • H:0x2 is identifier of a "scsi bus busy" condition.

Environment

VMware vSphere ESXi 6.5

Cause

This issue occurs due to known issues with in the in-box driver found in ESXi 6.5 GA (build 4564106) vmw_ahci_1.0.0-34.

Resolution

This issue is resolved in VMware ESXi 6.5 Update 1 or later, available at VMware Downloads.

Notes:

• The fix is now included vmw_ahci 1.0.0-37 and newer versions.
• VMware does not provide a standalone vmw_ahci driver update. The driver is updated when upgrading your ESXi host.

Workaround:
To work around this issue if you do not want to upgrade, switch to the old vmklinux AHCI driver as this is not impacted by this issue.