Potential Loss of Access When Using VMware VAAI Atomic Test-and-Set With V6.4.1.x Levels Earlier Than V6.4.1.4

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Flash – Reference #: S1004343

Abstract

VMware hosts using the Atomic Test-and-Set feature of the VAAI API with Storwize or SAN Volume Controller V6.4.1.x levels earlier than V6.4.1.4 may experience an issue that can cause multiple node or node canisters to reboot, potentially leading to temporary loss of host access.

Content

VMware hosts configured to use the Atomic Test-and-Set (ATS) feature of the VAAI API employ SCSI Compare and Write to control locking on Storwize and SAN Volume Controller volumes.

An issue exists in the handling of Compare and Write commands in V6.4.1.x releases earlier than V6.4.1.4 that can lead to multiple nodes rebooting simultaneously, which may cause a temporary loss of access to volumes presented by these nodes.

Customers are advised not to use the VMware ATS feature if they are running an affected release.

Please refer to VMware support documentation for instructions on how to disable the ATS feature.

Fix

This issue was resolved by APAR IC90455 in the V6.4.1.4 PTF release.

Important: 

The probability of experiencing this issue is increased during a system upgrade. It is therefore strongly recommended to disable ATS on all VMware hosts before upgrading from an affected release to V6.4.1.4 or higher.

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