PRIMECLUSTER Global Disk Services Configuration and Administration Guide 4.1 (Linux)

A.2.2 Restraining Access to Physical Special File

After registration of disks with GDS is complete, accessing the disks using physical special files as below becomes impossible. GDS prevents unintentional access by the users to physical special files in order to protect mirroring statuses.

/dev/sd[a-z]*[1-4]*

For example, if you execute the dd command to write to the disk with physical special file, the following error message will be displayed.

# dd if=/dev/zero of=/dev/sda1
dd: /dev/sda1: open: Device busy

Disk list output by the fdisk(8) command does not display the disk registered with GDS.

This access protection is cancelled when a disk is removed from a class.

It will also be cancelled when an object is used for disk swap. The access protection function will turn back on if disk recovery operation is performed on the object.

Access to physical special files is prevented on the following nodes:

• For disks that are registered with disk classes

  All of the nodes in the relevant domains

• For disks that are registered with shadow classes

  Nodes where the relevant shadow classes reside

For the following disks, access to physical special files is not prevented. Be careful not to access these physical special files.

• Disks that are registered with classes in other domains
• Disks that are registered with shadow classes on other nodes