To guard against accidental file system and data corruption, the device nodes of the component volumes are configured by default not to have raw and block entries in the
diskgroup directories. As a result, applications are prevented from directly reading from or writing to the component volumes of a volume set.
If some applications, such as the raw volume backup and restore feature of the Veritas NetBackupTM software, need to read from or write to the component volumes by accessing raw device nodes in the
diskgroup directory, this is supported by specifying additional command-line options to the
vxvset command. Access to the block device nodes of the component volumes of a volume set is unsupported.
All of the raw device nodes for the component volumes of a volume set can be created or removed in a single operation. Raw device nodes for any volumes added to a volume set are created automatically as required, and inherit the access mode of the existing device nodes.
Access to the raw device nodes for the component volumes can be configured to be read-only or read-write. This mode is shared by all the raw device nodes for the component volumes of a volume set. The read-only access mode implies that any writes to the raw device will fail, however writes using the
ioctl interface or by VxFS to update metadata are not prevented. The read-write access mode allows direct writes via the raw device. The access mode to the raw device nodes of a volume set can be changed as required.
The presence of raw device nodes and their access mode is persistent across system reboots.
Note the following limitations of this feature: