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Storage Foundation 7.3 Administrator's Guide - AIX

Last Published: 2019-07-23

Product(s): InfoScale & Storage Foundation (7.3)

Displaying VxFS file system usage on thin reclamation LUNs

Storage Foundation 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 per-LUN disk space usage for currently 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 -o fssize option maps the file system space usage to the underlying LUNs. The disk space usage statistics may differ slightly from the usage reported by other utilities because of the base unit used for the calculation.

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

The -o fssize option does not display the space used by cache objects or instant snapshots.
RAID5 format is not supported.
If the VxFS file system is not mounted, or if the device has both mounted and unmounted VxFS file systems, no information is displayed. The file system usage (FS_SIZE) column displays a dash (-).

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_SIZE 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.

DEVICE	The name of the VxVM disk, in either Enclosure-based naming (EBN) or OS-based naming (OSN).
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_SIZE	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.
RECLAIM_CMD	The reclamation method that DMP uses.

To display file system usage on all thin LUNs

To display the file system usage on all thin or thinrclm LUNs known locally to the system, use the following command:

$ vxdisk -o thin,fssize [-u unit] list

Where unit is a size unit for the display. For example:

$ vxdisk -o thin,fssize -u m list

DEVICE    SIZE      PHYS_ALLOC FS_SIZE GROUP  TYPE     RECLAIM_CMD
emc0_428a 16384.00m 6335.00m   610.00m  mydg  thinrclm  WRITE_SAME
emc0_428b 16384.00m 3200.00m    22.00m  mydg  thinrclm  WRITE_SAME
emc0_4287 16384.00m 6233.00m   617.00m  mydg  thinrclm  WRITE_SAME
emc0_4288 16384.00m 1584.00m  1417.00m  mydg  thinrclm  WRITE_SAME
emc0_4289 16384.00m 2844.00m  1187.00m  mydg  thinrclm  WRITE_SAME 
xiv0_030f 16384.00m 2839.00m  1223.00m  xivdg thinrclm  WRITE_SAME
xiv0_0307 16384.00m  666.00m   146.00m  xivdg thinrclm  WRITE_SAME
xiv0_0308 16384.00m  667.00m   147.00m  xivdg thinrclm  WRITE_SAME
xiv0_0309 16384.00m    3.00m   -        -     thinrclm  WRITE_SAME
xiv0_0310 16384.00m   30.00m   -        -     thinrclm  WRITE_SAME

Or, to display the file system usage on a specific LUN or enclosure, use the following form of the command:

$ vxdisk -o thin,fssize list [-u unit] disk|enclosure

For example:

$ vxdisk -o thin,fssize list emc0

DEVICE    SIZE(MB) PHYS_ALLOC(MB) FS_SIZE(MB) GROUP TYPE     RECLAIM_CMD
emc0_428a 16384    6335           610         mydg  thinrclm WRITE_SAME
emc0_428b 16384    6335           624         mydg  thinrclm WRITE_SAME
emc0_4287 16384    6335           617         mydg  thinrclm WRITE_SAME
emc0_4288 16384    1584           617         mydg  thinrclm WRITE_SAME
emc0_4289 16384    2844           1187        mydg  thinrclm WRITE_SAME

More Information

Determining when to reclaim space on a thin reclamation LUN