Under certain conditions, Guest OS UNMAP Operation may cause temporary slower performance after deleting and re-copying data that nearly fills the volume
Article ID: 407842
Updated On:
Products
Issue/Introduction
When a volume is nearly full, Broadcom has observed a condition whereby a file copy operation may encounter temporary performance degradation if copied immediately after file deletion due to guest OS UNMAP behavior.
On a VM running Windows guest OS with TRIM/UNMAP enabled, where the volume is nearly full, if a large file deletion is immediately followed by a file copy operation, that copy operation may observe slowness due to the way Windows issues TRIM.
Environment
VMware vSAN ESA 8.x & 9.x
Resolution
Broadcom recommends upgrading to the latest version of 8.x or 9.x, depending on the version currently in use for your environment, for improved performance. If you're still seeing slow performance after upgrading collect complete cluster logs during the time of the event, open a case with vSAN Support, and upload the logs for further investigation.
Additional Information
This issue is specific to environments where UNMAP is enabled in the guest OS and large file operations are performed in rapid succession on small volumes.
Feedback
