Critical Patch for All-Flash vSAN with Deduplication (6.0 and 6.5)

VMware has released a critical patch for vSAN 6.0 and 6.5. This patch contains a fix for a highly critical vSAN issue that might cause IO read errors and in some cases severe symptoms such as inaccessible VMs, host failures, or stuck resyncs. The issue manifests itself only under highly specific operations and IO patterns.

The bug only affects All-Flash vSAN configurations with deduplication enabled.

Symptoms for this issues are the following messages in the Events tab:

  • "vSAN detected an unrecoverable medium or checksum error for component uuid on disk group uuid."
  • "vSAN detected and fixed a medium or checksum error for component uuid on disk group uuid."

The following versions are affected according to KB2151042 and KB2151081.

Name Patch Date Build
ESXi 6.5 Update 1 ESXi650-update1 2017-07-27 5969303
ESXi 6.5 Update 1 (Security only) ESXi650-update1 2017-07-27 5969300
ESXi 6.5d (vSAN 6.6 Patch) ESXi650-201704001 2017-04-18 5310538
ESXi 6.5 Express Patch 1a ESXi650-201703002 2017-03-28 5224529
ESXi 6.5 Patch 1 ESXi650-201703001 2017-03-09 5146846
ESXi 6.5 Patch 1 (Security Only) ESXi650-201703001 2017-03-09 5146843
ESXi 6.5a ESXi650-201701001 2017-02-02 4887370
ESXi 6.5 GA 2016-11-15 4564106
ESXi 6.0 Update 3a (Patch 5) ESXi600-201706001 2017-06-06 5572656
ESXi 6.0 Update 3a (Patch 5) (Security Only) ESXi600-201706001 2017-06-06 5485776
ESXi 6.0 Express Patch 7a ESXi600-201703001 2017-03-28 5224934
ESXi 6.0 Update 3 ESXi600-update3 2017-02-24 5050593
ESXi 6.0 Update 3 (Security Only) ESXi600-update3 2017-02-24 5047589
ESXi 6.0 Patch 4 ESXi600-201611001 2016-11-22 4600944
ESXi 6.0 Patch 4 (Security Only) ESXi600-201611001 2016-11-22 4558694

VMware states that all vSAN customers using All-Flash with deduplication enabled must upgrade to this patch immediately:

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