Operational Defect Database
BugZero updated this defect 39 days ago.
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VMware | 76723
Memory snapshot of the VM when on VVOL is taking more time
Last update date:
4/10/2024
Affected products:
vSphere ESXi
Affected releases:
6.77.0
Fixed releases:
No fixed releases provided.
Description:
Symptoms
Memory snapshot of the VM running on a VVOL datastore takes more time compared to when VM is moved to VMFS datastore.Logs below show that every memory snapshot taken on a VM is quite slow and taking more time vmware-1.log:2019-08-23T02:16:49.372Z| vmx| I125: SnapshotVMX_TakeSnapshot start: 'VM Snapshot 23%252f08%252f2019, 03:16:48', deviceState=1, lazy=1, quiesced=0, forceNative=0, tryNative=1, saveAllocMaps=0 vmware-1.log:2019-08-23T02:28:18.002Z| vmx| I125: SnapshotVMXTakeSnapshotComplete: Done with snapshot 'VM Snapshot 23%252f08%252f2019, 03:16:48': 1 vmware-1.log:2019-08-23T11:19:26.613Z| vmx| I125: SnapshotVMX_TakeSnapshot start: 'VM Snapshot 23%252f08%252f2019, 12:19:25', deviceState=1, lazy=1, quiesced=0, forceNative=0, tryNative=1, saveAllocMaps=0 vmware-1.log:2019-08-23T11:32:38.908Z| vmx| I125: SnapshotVMXTakeSnapshotComplete: Done with snapshot 'VM Snapshot 23%252f08%252f2019, 12:19:25': 2 vmware-1.log:2019-08-23T20:27:49.878Z| vmx| I125: SnapshotVMX_TakeSnapshot start: 'VM Snapshot 23%252f08%252f2019, 21:27:48', deviceState=1, lazy=1, quiesced=0, forceNative=0, tryNative=1, saveAllocMaps=0 vmware-1.log:2019-08-23T20:41:27.978Z| vmx| I125: SnapshotVMXTakeSnapshotComplete: Done with snapshot 'VM Snapshot 23%252f08%252f2019, 21:27:48': 3 vmware-1.log:2019-08-24T13:56:13.224Z| vmx| I125: SnapshotVMX_TakeSnapshot start: 'VM Snapshot 24%252f08%252f2019, 14:56:10', deviceState=1, lazy=1, quiesced=0, forceNative=0, tryNative=1, saveAllocMaps=0 vmware-1.log:2019-08-24T14:10:49.290Z| vmx| I125: SnapshotVMXTakeSnapshotComplete: Done with snapshot 'VM Snapshot 24%252f08%252f2019, 14:56:10': 4
Cause
Low priority I/O throttling is taking place when memory snapshots on VM located on a VVOL datastore
Impact / Risks
Memory snapshot of the VM running on a VVOL datastore takes more time compared to when VM is moved to VMFS datastore.
Resolution
An improvement in memory snapshot for SCSI vVols has been implemented and it is included in vSphere 7.0 U3c.
Workaround
As a workaround you can follow the steps below (make sure to have valid backups before performing any changes):1. Power off the VM2. Take a backup of the vmx file. 3. Add the following parameters in vmx configuration file and save. mainMem.ioBlockPages = "2048"mainMem.iowait = "1" 4. Reload the vmx file, see: Reloading a vmx file without removing the virtual machine from inventory (1026043) 5. Power on the vm.
