vSAN nodes experience LSOM Memory congestion due to high "Number of elements in commit tables" (vSAN 7.0 U3/8.0 GA)

Products

• VMware vSAN 7.x
• VMware vSAN 8.x

Issue/Introduction

This KB addresses LSOM memory congestion issues resulting in vSAN Memory congestion impacting builds prior to 7.0 Update 3 P06 (build: 20842708) or prior to ESXi 8.0 EP1 (build: 20842819).

The symptoms and validation scripts in KB vSAN nodes experience LSOM Memory congestion due to high "Number of elements in commit tables" (vSAN 6.7 U3/vSAN 7.0 U1) are the same for this issue.

Environment

VMware vSAN 7.0.3
VMware vSAN 8.0.0

Cause

This issue is similar in cause and symptoms to the issue outlined in KB vSAN nodes experience LSOM Memory congestion due to high "Number of elements in commit tables" (vSAN 6.7 U3/vSAN 7.0 U1), however, this issue can occur regardless of whether the esxcfg-advcfg configurations described in that KB are configured to the default values of later builds or the workaround described in that KB has been applied (e.g. /VSAN/ObjectScrubPersistMin is set to 0).

This issue occurs in clusters where there are larger objects (which have a concatenated component layout) and is more likely to occur when these larger objects are IO-intensive.

Resolution

This issue is resolved in:
ESXi 7.0 Update 3 P06 (build: 20842708)
ESXi 8.0 EP1 (build: 20842819)

 

Workaround:

The impacted Disk-Groups commit-table entries (and thus also the Memory congestion) can be cleared by unmounting and mounting the impacted Disk-Group.

If unmount and mount of the Disk-Groups via the vSphere UI or via CLI is not possible then rebooting the node with congested Disk-Group(s) will also automatically unmount and mount the Disk-Groups as part of node restart process, Maintenance Mode with Ensure Accessibility option may not be possible depending on the severity of the issue.