Changes related to Veritas Volume Manager

Veritas Volume Manager (VxVM) includes the following changes in 6.0:

Creating a volume of maximum size

In previous releases, Veritas Volume Manager provided a two-step approach to creating a volume of the maximum size. You had to run the vxassist maxsize command to find the maximum size of the volume to be created with the given constraints. Then, you had to run the vxassist make command and specify the volume size as the maximum determined by the vxassist maxsize command.

In this release, you can create a maximum sized volume with a single command. Specify the vxassist make command with the maxsize keyword. The vxassist command creates the maximum sized volume possible, taking into consideration any other allocation attributes that you specify.

Changes to the instant snapshot (version 20) data change object (DCO) volume layout

In this release, the volume layout of the data change object (DCO) has been changed to improve the I/O performance and scalability of instant snapshots. The change in layout does not alter how you administer instant snaphosts. The only visible effect is in improved I/O performance and in some cases, increased size of DCO volume. As with previous releases, you create DCOs for instant snapshots using "vxsnap prepare" or by specifying "logtype=dco dcoversion=20" while creating volume with "vxassist make".

The instant snapshot DCO (previously known as a version 20 DCO) now uses dynamic creation of maps on the preallocated storage. The size of the DRL (Dirty region logging) map does not depend on volume size and can be configured using drlmapsz while creating DCO volume.

Veritas Volume Manager throttling of administrative I/O

In this release, Veritas Volume Manager (VxVM) provides throttling of administrative I/O. During heavy I/O loads, VxVM throttles I/O that it creates to do administrative operations. This behavior ensures that the administrative I/Os do not affect the application I/O performance. When the application I/O load is lighter, VxVM increases the bandwidth usage for administrative I/O operations.

VxVM automatically manages the I/O throttling for administrative tasks, based on its perceived load on the storage. Currently, I/O throttling is supported for the copy operations which use ATOMIC_COPY and involve one destination mirror. The I/O throttling is transparent, and does not change the command usage or output. The following commands are supported:

  • vxassist mirror

  • vxassist snapcreate

  • vxevac

  • vxplex att

  • vxplex cp

  • vxplex mv

  • vxprint

  • vxsnap addmir

  • vxsnap reattach

  • vxsd mv

  • vxtune

The administrative I/O operations allocate memory for I/O from a separate memory pool. You can tune the maximum size of this pool with the tunable parameter, vol_max_adminio_poolsz.

See the Veritas Storage Foundation Tuning Guide for information about tuning the vol_max_adminio_poolsz parameter.

Command completion for Veritas commands

Veritas Storage Foundation Cluster File System High Availability now supports command completion for Veritas Volume Manager (VxVM) commands and Dynamic Multi-Pathing (DMP) commands. In this release, command completion is supported only on the bash shell. The shell must be bash version 2.4 or later.

To use this feature, press Tab while entering a supported VxVM or DMP command. The command is completed as far as possible. When there is a choice, the command completion displays the next valid options for the command. Enter one of the displayed values. A value in brackets indicates a user-specified value.

Note:

Platform-specific options are not supported with command completion in this release.

The following commands support command completion:

  • vxassist

  • vxdisk

  • vxplex

  • vxprint

  • vxsnap

  • vxstat

  • vxtune

  • vxcache

  • vxconfigd

  • vxtask

  • vxreattach

  • vxdmpadm

  • vxddladm

  • vxvol

  • vxcdsconvert

  • vxresize

  • vxdctl

  • vxsd

  • vxdisksetup

  • vxdiskunsetup

  • vxrecover

  • vxedit

  • vxdg

  • vxclustadm

vxdisk -o thin list command now shows the disk space used by a VxFS file system

The vxdisk -o thin list command now shows the disk space used by a VxFS file system.