Customizing allocation behavior

By default, the vxassist command creates volumes on any available storage that meets basic requirements. The vxassist command seeks out available disk space and allocates it in the configuration that conforms to the layout specifications and that offers the best use of free space. The vxassist command creates the required plexes and subdisks using only the basic attributes of the desired volume as input.

If you are provisioning Storage Foundation on thin storage, you should understand how Storage Foundation works with thin storage.

Additionally, when you modify existing volumes using the vxassist command, the vxassist command automatically modifies underlying or associated objects. The vxassist command uses default values for many volume attributes, unless you provide specific values to the command line. You can customize the default behavior of the vxassist command by customizing the default values.

See Setting default values for vxassist.

The vxassist command creates volumes in a default disk group according to the default rules. To use a different disk group, specify the -g diskgroup option to the vxassist command.

If you want to assign particular characteristics for a certain volume, you can specify additional attributes on the vxassist command line. These can be storage specifications to select certain types of disks for allocation, or other attributes such as the stripe unit width, number of columns in a RAID-5 or stripe volume, number of mirrors, number of logs, and log type.

For details of available vxassist keywords and attributes, refer to the vxassist(1M) manual page.

You can use allocation attributes to specify the types of allocation behavior shown in Table: Types of allocation behavior

Table: Types of allocation behavior

Allocation behavior


Layouts for the volumes

See Creating volumes of a specific layout.

Media types

See Creating volumes on specific media types.

Specific disks, subdisks, plexes locations

See Creating a volume on specific disks.

Ordered allocation

See Specifying ordered allocation of storage to volumes.

Site-based allocation

See Site-based allocation.

Setting the read policy

See Changing the read policy for mirrored volumes.

The vxassist utility also provides various constructs to help define and manage volume allocations, with efficiency and flexibility.

See Setting default values for vxassist.

See Using rules to make volume allocation more efficient.

See Understanding persistent attributes.

See Customizing disk classes for allocation.

See Specifying allocation constraints for vxassist operations with the use clause and the require clause.

See Management of the use and require type of persistent attributes .

More Information

About thin optimization solutions in Storage Foundation

Rules for determining the default disk group