Displaying VxFS file system usage on thin reclamation LUNs

Storage Foundation Cluster File System High Availability can discover and display the disk space usage for Veritas File System (VxFS) file systems on thin or thinrclm devices. The VxFS file systems must be mounted on Veritas Volume Manager (VxVM) volumes. The usage information can help you decide when to perform thin reclamation of a file system.

To report the disk space usage for mounted VxFS file systems on VxVM volumes, use the vxdisk -o thin -o fssize list command. The command displays the amount of disk space that currently contains files and is actively in use by the VxFS file system. The usage does not include any space that is allocated to the file system but was freed by deleting files. If more than one mounted VxFS file system uses the device, the file system usage column displays the consolidated space usage.

The following limitations apply to the command to display file system usage:

You can display the size and usage for all thin or thinrclm LUNs, or specify an enclosure name or a device name. If you specify one or more devices or enclosures, the command displays only the space usage on the specified devices. If the specified device is not a thin device or thinrclm device, the device is listed but the FS_USAGE column displays a dash (-).

If a VxFS file system spans multiple devices, you must specify all of the devices to display the entire file system usage. If you specify only some of the devices, the file system usage is incomplete. The command ignores the file system usage on any devices that are not specified.

Note:

The command can potentially take a long time to complete depending on the file system size, the level of fragmentation, and other factors. The command creates a task that you can monitor with the vxtask command.

The command output displays the following information.

SIZE

The size of the disk; that is, the size that is presented to the file system. This size represents the virtual size rather than the actual physical space used on the device.

PHYS_ALLOC

The physical allocation on the array side. This size represents the physical space that is allocated as the application writes to the file system. When the files are deleted or changed, the physical space remains allocated until a reclamation is performed. In this case, the physical size includes some unused space.

FS_USAGE

The physical space Veritas File System (VxFS) file systems are using. The VxFS file systems must be mounted on VxVM volumes. The information is displayed only for thin provisioning capable (thin) or thin reclamation capable (thinrclm) LUNs.

GROUP

The disk group that contains the disk.

TYPE

The type of thin devices - thin provisioning capable (thin) or thin reclamation capable (thinrclm). The vxdisk -o thin list command displays thick disks only if you explicitly specify the disk name on the command line.

To display file system usage on all thin LUNs

More Information

Determining when to reclaim space on a thin reclamation LUN