The VMFS3 dashboard helps you visualize how bad are the “Long VMFS3 rsv time” issues.
This message is logged when a SCSI Reserve/Release operation (SCSI Reservation > Perform I/O > SCSI Release) takes longer than expected to complete. The expected reservation time is very fast, and if the reservation time exceeds 200ms, this message is reported. This is defined as the maximum reserve time or Scsi.MaxReserveTime.
2014-12-10T18:43:57.374Z esx.vmware.com vmkernel: cpu3:9751)FS3Misc: 1440: Long VMFS3 rsv time on 'datastore_name' (held for 1156 msecs). # R: 1, # W: 1 bytesXfer: 5 sectors
Thanks to Kibana’s Micro Analysis tool, you’ll quickly catch the guilty datastores: