VxVM DISK Group

VxVM Disk Group

• A disk group is a collection of volume manager disks grouped together to hold the data. All the configuration changes made to a disk group are applied to the disks in that disk group only. 

• Volume Manager objects cannot span disk groups i.e. all the operations on a particular disk group remains confined to that particular group.

• Disk groups enable high availability as these can be shared by two or more hosts but can be accessed by only one host at a time. In two hosts and a shared storage situation one host can take over the ownership of the disk groups and drives in case other host fails.

Plex

Plex

A plex is a structured or ordered collection of subdisks that represents one copy of the data in a volume. A plex consists of one or more subdisks located on one or more physical disks.

The default naming convention for plexes in a volume is volumename-##. The default plex name consists of the volume name, a hyphen, and a two-digit number

A plex is also called a mirror. The terms plex and mirror can be used interchangeably, even though a plex is only one copy of the data. The terms "mirrored" or "mirroring" imply two or more copies of data.

Creating a Plex

# vxmake –g <diskgroup> plex <plexname>  sd=<sdname>

Removing a Plex

# vxplex –o rm disk <plex>

# vxplex –g <group> dis <plex>

# vxedit –g <group> -rf rm <plex>

Moving a Plex

# vxplex mv <original plex> <new plex>

Copying a Plex

# vxplex cp <volume> <new plex>

Attaching a plex

# vxplex att <volume> <plex>

Detaching a plex

# vxplex det <plex>

Disassociating plex

# vxplex –g <diskgroup> -o rm dis <plexname>

Off lining a plex

# vxmend off vol01-02

Renaming a Plex

# vxedit -g <diskgroup> rename oldplex newplex

Creating a Subdisk

Creating a Subdisk

# vxmake –g <diskgroup> sd disk1-01 disk1,0,100m

This would create a sub-disk called disk1-01 at the start of disk disk01 and would be 100m long.

If you want to create another sub-disk on the same disk (disk01) the offset would be 100m as this is where the next freespace would be on the disk. So

# vxmake –g <diskgroup> sd disk01-02 disk1,100m,100m

This would create another 100m subdisk.

Removing Subdisk

# vxedit rm <sub-disk>

Moving sub-disk

# vxsd mv <old sub-disk> <new sub-disk>

Associating with a plex

# vxmake plex <plex> sd=<sub-disk>

# vxmake plex home-1 sd=disk02-01, disk02-00, disk02-02

Dissociating a Sub-disk

# vxsd dis <sub-disk>

Splitting a Subdisk

# vxsd –s<size> split sd<new sub><newsub2>

Joining a Subdisk

# vxsd join <subdisk1><subdisk2><newsubdisk>

Evacuate the subdisk from one of the disk in the volume

# /etc/vx/bin/vxevac –g <dg_name> <dm_name_old> <dm_name_new>

# /etc/vx/bin/vxevac –g ccdg ccdg01 ccdg02

VXVM Disk Types and Formats

·         auto: Automatically configured by VxVM

·         auto-cdsdisk           (Default for 4.0)

·         auto-simple

·         auto-sliced

·         auto-none

·         Simple: Public and private regions are contiguous on the same partition.