6.5.1

Table Of Contents
ATS+SCSI Mechanism
A VMFS datastore that supports the ATS+SCSI mechanism is configured to use ATS and attempts to use
it when possible. If ATS fails, the VMFS datastore reverts to SCSI reservations. In contrast with the ATS
locking, the SCSI reservations lock an entire storage device while an operation that requires metadata
protection is performed. After the operation completes, VMFS releases the reservation and other
operations can continue.
Datastores that use the ATS+SCSI mechanism include VMFS5 datastores that were upgraded from
VMFS3. In addition, new VMFS5 or VMFS6 datastores on storage devices that do not support ATS use
the ATS+SCSI mechanism.
If your VMFS datastore reverts to SCSI reservations, you might notice performance degradation caused
by excessive SCSI reservations. For information about how to reduce SCSI reservations, see the
vSphere Troubleshooting documentation.
Display VMFS Locking Information
Use the esxcli command to obtain information about the locking mechanism that a VMFS datastore
uses.
In the procedure, --server=server_name specifies the target server. The specified target server
prompts you for a user name and password. Other connection options, such as a configuration file or
session file, are supported. For a list of connection options, see Getting Started with vSphere Command-
Line Interfaces.
Prerequisites
Install vCLI or deploy the vSphere Management Assistant (vMA) virtual machine. See Getting Started with
vSphere Command-Line Interfaces. For troubleshooting, run esxcli commands in the ESXi Shell.
Procedure
u
To display information related to VMFS locking mechanisms, run the following command:
esxcli --server=server_name storage vmfs lockmode list
The table lists items that the output of the command might include.
Table 174. VMFS Locking Information
Fields Values Descriptions
Locking Modes Indicates the locking configuration of the
datastore.
ATS-only
The datastore is configured to use the
ATS-only locking mode.
ATS+SCSI
The datastore is configured to use the
ATS mode. If ATS fails or is not supported,
the datastore can revert to SCSI.
vSphere Storage
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