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

Flash (Alert)


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 6.0 or later. However, ATS Heartbeating is still not supported on VMware vSphere ESXi 5.5 environments.

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
Segment Product Component Platform Version Edition
Disk Storage Systems IBM Storwize V5000 7.5 Platform Independent 7.1, 7.2, 7.3, 7.4, 7.5, 7.6
Disk Storage Systems IBM Storwize V3700 (2072) 7.5 Platform Independent 6.4, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6
Disk Storage Systems IBM Storwize V3500 (2071) 7.5 Platform Independent 6.4, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6
Disk Storage Systems Flex System V7000 7.2 Platform Independent 6.4, 7.1, 7.2
Storage Virtualization SAN Volume Controller 7.5 SAN Volume Controller 6.4, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6

Document information

More support for: IBM Storwize V7000 (2076)
7.4

Version: 6.4, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6

Operating system(s): IBM Storwize V7000

Reference #: S1005201

Modified date: 05 June 2017


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