Encrypted Volume and File System v1.1 Administrator's Guide

5. Do not create an EMD area for the EVFS volume. The backup volume inherits a copy of the
EMD from the original volume. However, because the backup volume inherits its EMD, the
dirty bit is set even though the backup volume has not been enabled. You must reset the
dirty bit in the EMD of the backup volume using the evfsvol check –r command. The
syntax is as follows:
evfsvol check -r evfs_volume_path
Where evfs_volume_path is the absolute pathname for the EVFS volume device file.
For example:
# evfsvol check -r /dev/evfs/vg01/lvol5backup
Encrypted volume "/dev/evfs/vg01/lvol5backup" has not been properly shut down.
Resetting dirty bit...
Encrypted volume "/dev/evfs/vg01/lvol5backup" has been successfully recovered
6. Open raw access to the backup EVFS volume using the evfsvol raw command.
CAUTION: After you open the volume for raw access, any entity reading data from the
EVFS volume receives encrypted data. Any entity writing data to the EVFS volume writes
directly to the underlying disk; EVFS does not encrypt the text. HP recommends that you
use the evfsvol raw command only when creating encrypted backup media or restoring
encrypted backup media.
The syntax for the evfsvol raw command is as follows:
evfsvol raw evfs_volume_path
where evfs_volume_path is the absolute pathname for the EVFS volume device file.
For example:
# evfsvol raw /dev/evfs/vg01/lvol5backup
7. Use a block device utility such as dd to copy data from the EVFS backup volume to the target
device. For example:
# dd bs=64k if=/dev/evfs/vg01/lvol5backup of=/dev/rmt/0m
8. Close raw access to the backup EVFS volume using the evfsvol close command to begin
the procedure to return the backup volume to its original state. For example:
# evfsvol close /dev/evfs/vg01/lvol5backup
9. Unmap the backup EVFS volume using the evfsadm unmap command. For example:
# evfsadm unmap /dev/evfs/vg01/lvol5backup
10. Merge the backup volume back with the original LVM volume using the lvmerge command.
For example:
# lvmerge /dev/vg01/lvol5backup /dev/vg01/lvol5
Example
In the following example, the administrator splits the /dev/vg01/lvol5 mirror volume and
creates the /dev/vg01/lvol5backup volume. The target is the /dev/rmt/0m tape device.
The dd command receives encrypted text from the source EVFS volume because the volume is
open for raw access.
# lvsplit –s backup /dev/vg01/lvol5
# evfsvol map /dev/vg01/lvol5backup
# evfsvol check -r /dev/evfs/vg01/lvol5backup
# evfsvol raw /dev/evfs/vg01/lvol5backup (EVFS prompts if you want to continue.)
# dd bs=64k if=/dev/evfs/vg01/lvol5backup of=/dev/rmt/0m
# evfsvol close /dev/evfs/vg01/lvol5backup
# evfsadm unmap /dev/evfs/vg01/lvol5backup
# lvmerge /dev/vg01/lvol5backup /dev/vg01/lvol5
106 Backing Up and Restoring Data on EVFS Volumes