Unable to create vSAN disk group with error : "Unable to create LSOM file system for vSAN disk naa.################# please see VMkernel log for more details"
Article ID: 443352
Updated On:
Products
Issue/Introduction
- Attempting to add or recreate the disk groups in "vCenter UI > vSAN Cluster > Configure > Disk Management" throws below error:
A general system error occurred: Unable to create LSOM file system for vSAN disk naa.########################### please see VMkernel log for more details
- Newly created disk group may display an unhealthy status.
Environment
VMware vSAN (ALL Versions)
Cause
Disk group creation is failing and reports to be unhealthy due to LSOM heap memory exhaustion
- Disk group creation or expansion fails because the default LSOM
"heapSize"has reached its maximum limit.
2026-05-27T06:49:33.761Z Wa(180) vmkwarning: cpu96:2100146)WARNING: Heap: 3670: Heap LSOM already at its maximum size. Cannot expand.2026-05-27T06:49:33.761Z Wa(180) vmkwarning: cpu96:2100146)WARNING: LSOM: LSOMSSDLOGOpen:8214: Unable to initialize RC SSD context for disk ########-####-####-####-############: Out of memory2026-05-27T06:49:33.761Z Wa(180) vmkwarning: cpu84:2647787)WARNING: LSOM: LSOMAddDiskGroupDispatch:10070: Failed to add disk group. SSD ########-####-####-####-############: Out of memory2026-05-27T06:49:33.762Z In(182) vmkernel: cpu37:2647653)PLOG: PLOGVerifyDiskGroupNotifyCompletion:5634: Notify disk group failed for SSD UUID ########-####-####-####-############ :Out of memory was recovery complete ? Yes
Resolution
Follow the below steps on all ESXi hosts in the cluster to fix the LSOM heap issues.
Verify the current LSOM heap size:
esxcfg-advcfg -g /LSOM/heapSizeIncrease the LSOM heap size in MB:
esxcfg-advcfg -s <heapSize> /LSOM/heapSize ( 2047 is the Maximum heapSize which can be increased)Perform a rolling reboot of all hosts (place into Maintenance Mode with Ensure Accessibility).
Once all hosts are rebooted, retry the disk group recreation.
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