Advanced vSAN configuration in sync for LSOM.blPLOGCacheLines and LSOM.blPLOGLsnCacheLines

Products

• VMware vSAN

Issue/Introduction

• vSAN Skyline Health reports an alarm: "Advanced vSAN configuration in sync"
  
  

• Health check details highlight mismatched parameters: /LSOM/blPLOGCacheLines and /LSOM/blPLOGLsnCacheLines.

Environment

VMware vSAN 7.x
VMware vSAN 8.x

Cause

Mismatch in advanced settings /LSOM/blPLOGLsnCacheLines and /LSOM/blPLOGCacheLines on hosts is causing the Advanced vSAN Configuration in Sync check to fail.
These parameters must be consistent across all hosts to maintain vSAN stability and performance.

Resolution

Recommended to update the advanced settings on the affected hosts to ensure consistency across the vSAN cluster.

Use the following commands to apply the values:

To get the values:
esxcfg-advcfg --get /LSOM/blPLOGLsnCacheLines 
Value of blPLOGLsnCacheLines is #####

esxcfg-advcfg --get /LSOM/blPLOGCacheLines 
Value of blPLOGCacheLines is #####

To set the values:
esxcfg-advcfg --set 131072 /LSOM/blPLOGLsnCacheLines
esxcfg-advcfg --set 4096 /LSOM/blPLOGCacheLines

Host need to be restarted for the changes to be effective.

Additional Information:

/LSOM/blPLOGLsnCacheLines It states number of lsn cache lines for in PLOG (Requires Reboot)
Default value: 4096
Risk of Adjusting parameter: Increasing it will increase the memory usage and reduce the CPU usage and vice-versa if they are decreased.

/LSOM/blPLOGCacheLines It states number of cache lines for bucketlist in PLOG
Default value: 131072
Risk of Adjusting parameter: Increasing it will increase the memory usage and reduce the CPU usage and vice-versa if they are decreased.