Sunday, April 13, 2008

VERITAS What is auto:cdsdisk

What is cdsdisk?
c1t0d0s2 auto:cdsdisk data1dg01 data1dg online
ANS: For a disk to be accessible by multiple platforms, the disk must be consistently recognized by the platforms, and all platforms must be capable of performing I/O on the disk. CDS disks contain
specific content at specific locations to identify or control access to the disk on different platforms.
The same content and location are used on all CDS disks, independent of the platform on which the
disks are initialized.


VERITAS Volume Manager (tm) 4.0 revised vxdg init default options ( cds=off ) need to be specified for all non-cdsdisk types when creating a new disk group.

Details:
In VERITAS Volume Manager 4.0, changes were made to the default disk group type and disk type attributes. Prior to Volume Manager 4.0, the default disk type was "simple" it is now "cdsdisk". If a device has a disk type of "cdsdisk", the additional vxdg init attribute is not required ( cds=off ).

Example
-------------
Create a new disk group using a cdsdisk type defined disk:

DEVICE TYPE DISK GROUP STATUS
c0t0d0s2 auto:none - - online invalid
c1t0d1s2 auto:cdsdisk - - online <-- Using this disk for this exercise
c1t0d2s2 auto:sliced - - online
c1t0d3s2 auto:sliced - - online
c1t0d8s2 auto:sliced ctd1 emcdg online
c1t0d10s2 auto:sliced - - online invalid
emcpower8c simple emc8 rootdg online
emcpower9c simple - - online

CDSDISK
# vxdg init testdg c1t0d1s2
The vxdg init command works fine, without the need for the "cds=off" argument as the disk type was cdsdisk.

Revised output:
c1t0d1s2 auto:cdsdisk c1t0d1s2 testdg online

Simple or sliced disk:
Sliced:
# vxdg init testdg2 c1t0d1s2
VxVM vxdg ERROR V-5-1-6478 Device c1t0d1s2 cannot be added to a CDS disk group

Workaround:
Add the cds=off argument:
# vxdg init testdg2 c1t0d1s2 cds=off

Simple:

# vxdg init newemcdg disk01=emcpower9c
VxVM vxdg ERROR V-5-1-6478 Device emcpower9c cannot be added to a CDS disk group

Now add the new attribute cds=off:
# vxdg init newemcdg disk01=emcpower9c cds=off
Revised output:
emcpower9c simple disk01 newemcdg online

Further Information
If the "cds=off" attribute is not specified with the vxdg init command, the /etc/default/vxdg file is searched for a definition of this attribute. If no such definition is found, the value "cds=on" is assumed. Add such a definition to this file if you wish to change the new default back.