IBM Support

Host Disconnects Using VMware vSphere 5.5 Update 2, 5.5 Update 3, 6.0, 6.0 Update 1 and 6.0 Update 2

Flashes (Alerts)


Abstract

VMware vSphere 5.5 Update 2, 5.5 Update 3, 6.0, 6.0 Update 1 and 6.0 Update 2 hosts may experience multiple repeated disconnects leading to application outages in response to delays in completing heartbeat I/O.

Content

A change was introduced in VMware vSphere 5.5 Update 2 and vSphere 6.0 to use Atomic Test and Set (ATS) by default for heartbeat I/O.

The use of ATS heartbeating is now supported on IBM SAN Volume Controller, Storwize and Spectrum Virtualize systems running 7.6.1.x code or later, with VMware vSphere environments using ESXi 6.0u3 or later. However, ATS Heartbeating is still not supported on VMware vSphere ESXi 5.5 environments. Please note that "ATS Heartbeats" and "ATS for Hardware Accelerated Locking" are two separate settings. The issue reported by this flash only applies to ATS Heartbeats.

To enable ATS heartbeating on a particular host, use the following command

VMFS-5:

  • esxcli system settings advanced set -i 1 -o /VMFS3/useATSForHBOnVMFS5

Due to the low timeout value for heartbeat I/O using ATS, this can lead to host disconnects and application outages if delays of 8 seconds or longer are experienced in completing individual heartbeat I/Os on backend storage systems or the SAN infrastructure.

Workaround

Release 7.6.0 introduced enhancements to the way that SVC and Storwize process ATS, which will reduce the likelihood of experiencing this issue.

To prevent VMware hosts on these levels from experiencing this issue, the following commands can be issued to disable using ATS for heartbeat I/O and revert to the 5.5 Update 1 heartbeat method. Note that after issuing these commands, the host will NOT be required to be rebooted.

VMFS-3:

  • esxcli system settings advanced set -i 0 -o /VMFS3/useATSForHBOnVMFS3

(N.B. ATS for heartbeat is disabled by default with VMFS-3, so this command will only need to be issued if it has previously been manually enabled)

 

VMFS-5:

  • esxcli system settings advanced set -i 0 -o /VMFS3/useATSForHBOnVMFS5
 

Refer to the following VMware Knowledge Base article for more details on how to query and modify these settings:

For any queries about the above commands, contact VMware support.



Cross reference information
Product Component Platform Version Edition
IBM Storwize V5000 Platform Independent 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 8.1, 8.2
IBM Storwize V3700 (2072) Platform Independent 6.4, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8
IBM Storwize V3500 (2071) Platform Independent 6.4, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8
Flex System V7000 Platform Independent 6.4, 7.1, 7.2
SAN Volume Controller Platform Independent 6.4, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 8.1, 8.2
IBM FlashSystem 9100 family Platform Independent 8.2

Document information

More support for: IBM Storwize V7000 (2076)

Version: 6.4, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 8.1, 8.2

Operating system(s): Platform Independent

Reference #: S1005201

Modified date: 20 March 2019