VERITAS Storage Foundation 4.1 Cross-Platform Data Sharing Administrator's Guide

Non-CDS Disk Groups
6 VERITAS Storage Foundation CDS Administrator’s Guide
◆ Encapsulated disks.
Note On Solaris and Linux systems, the process of disk encapsulation places the slices or
partitions on a disk (which may contain data or file systems) under VxVM control. On AIX
and HP-UX systems, LVM volumes may be similarly be converted to VxVM volumes.
Device Quotas
Device quotas limit the number of objects in the disk group which create associated device nodes in
the file system. (This is useful for disk groups which share serially between Linux with a pre-2.6
kernel and other supported platforms. Prior to the 2.6 kernel, Linux supported only 256 minor
devices per major device.)
You can limit the number of devices that can be created in a given CDS disk group by setting the
device quota (refer to “Setting Device Quotas for CDS Disk Groups” on page 28).
When you create a device, an error is returned if the number of devices would exceed the device
quota. You then either need to increase the quota, or remove some objects using device numbers,
before the device can be created.
See also “Displaying Device Quotas for CDS Disk Groups” on page 33 for instructions on
displaying the device quota value.
Minor Device Numbers
Importing a disk group will fail if it will exceed the maximum devices for that platform.
Note There is a large disparity between the maximum number of devices allowed for devices on
the Linux platform with a pre-2.6 kernel, and that for other supported platforms.
Non-CDS Disk Groups
Any version 110 (or greater) disk group (DG) can contain both CDS and non-CDS disks. However,
only version 110 (or greater) disk groups composed entirely of CDS disks have the ability to be
shared across platforms. Whether or not that ability has been enabled is a license-controlled
attribute of the disk group (the cds attribute). Enabling that attribute causes a non-CDS disk group
to become a CDS disk group.
Although a non-CDS disk group can contain a mixture of CDS and non-CDS disks having
dissimilar private region alignment characteristics, its disk group alignment will still direct how all
subdisks are created.