"Thin provisioned volume capacity threshold reached" vCenter alarm triggered

Products

• VMware vSphere ESXi
• VMware vSphere ESX 7.x
• VMware vSphere ESX 8.x

Issue/Introduction

• The thin-provisioned storage devices meet their soft threshold and in vCenter Alarms are triggered "Thin provisioned volume capacity threshold reached".
• You receive a warning with an indication that the LUN reached a thin provisioning soft threshold.
  
   
  
  
  
  
  

Environment

• VMware vSphere ESXi 7.0

• VMware vSphere ESXi 8.0

Cause

• This Alarm is triggered when threshold for a LUN is met/exceeded in an environment that utilises thin-provisioned devices or storage pools.

• The initial threshold can be set as either soft or hard; however, only a hard threshold will prevent any further data from being allocated.

• Alarm trigger definition:

  
  

• In the /var/log/vobd.log file of the ESXi host, you see entries similar to:

  Space utilization on the thin-provisioned device naa.xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx exceeded the configured threshold.

• In the /var/log/vmkernel.log file of the ESXi host, you see entries similar to:

  ####-##-##T##:##:##.###Z cpu59:33773)NMP: nmp_ThrottleLogForDevice:3333: Cmd 0x8a (0x43be1e8451c0, 81679675) to dev "naa.xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" on path "vmhba##:C#:T#:L##" Failed: H:0x0 D:0x2 P:0x0 Valid sense data: 0x6 0x38 0x7. Act:NONE
####-##-##T##:##:##.###Z cpu59:33773)WARNING: ScsiDeviceIO: 2420: Space utilization on thin-provisioned device naa.xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx exceeded configured threshold 

Notes:

• When the warning limit is reached, the array sends a soft threshold error asc/q: 0x38/0x7 and the ESXi host continues to write.

• When the array runs out of disk space, a hard permanent error asc/q: 0x27/0x7 is sent.

• If the storage array has a Storage provider registered in the VC then the Storage array plugin will trigger the alarm though vCenter's /var/log/vmware/vmware-sps/sps.log:

  2026-07-21T14:25:50.073+08:00 [pool-27-thread-5] INFO  opId=sps-Main-996905-822 com.vmware.vim.sms.provider.vasa.alarm.AlarmDispatcher - [processAlarms] ProviderId ########-####-####-####-############
AlarmId 1492
AlarmType SpaceCapacity
ObjectId <storage_device_uuid>
ObjectTypeStorageLun
Status Yellow
MessgaeId Alarm.FSCapacity.NearlyFull

Resolution

1. Investigate from the storage array end about the space consumption of storage LUN which is reporting the alert.

2. Add additional space to the backing storage pool on the array if the utilization is legitimately high.

3. If space consumption on VMFS datastore is lesser than the backend storage device, consider performing UNMAP if it already has not been triggered - Storage array space not reclaimed after Guest OS cleanup on VMFS.

4. Contact the storage vendor if it is not possible to identify the affected storage device in the vSphere environment.

Additional Information