Veritas Volume Manager 5.0 Administrator's Guide (September 2006)

106 Administering disks
Extended Copy Service
Resizing a device that contains the only valid configuration copy for a disk group can
result in data loss if a system crash occurs during the resize.
Resizing a virtual disk device is a non-transactional operation outside the control of
VxVM. This means that the resize command may have to be re-issued following a system
crash. In addition, a system crash may leave the private region on the device in an
unusable state. If this occurs, the disk must be reinitialized, reattached to the disk group,
and its data resynchronized or recovered from a backup.
Extended Copy Service
The Extended Copy Service feature of VxVM works in tandem with the extended copy
engines from array vendors. When VxVM detects that the source and destination devices
are enabled for extended copy, VxVM automatically off loads copy requests to the array’s
copy manager.
The benefits of the Extended Copy Service are:
■ Non-disruptive copy operations from disk to disk. The host server remains online
during the copy and the data being copied remains accessible to the server.
■ Server-free copy operation. The copy operation is done between the array subsystem
and the target disk. The data copy operation does not use any CPU or I/O resources
on the host server.
To see whether the Extended Copy Service feature is enabled on a disk, use the
vxprint
command as shown in the following example. The feature is enabled if an
ecopy_enabled entry appears in the
flags line.
# vxprint -l disk03
Disk group: rootdg
Disk: disk03
info: diskid=1234567890.59.vm250e1.veritas.com
assoc: device=c2t2d0s2 type=auto
flags: autoconfig ecopy_enabled
device: path=/dev/vx/dmp/c2t2d0s4
devinfo: publen=35354136 privlen=9167
Note: If required, you can use the -o noecopy option to turn off Extended Copy Service
for each invocation of the
vxplex att, cp, mv and snapstart commands, and the vxsd
mv command.
Enabling a disk for Extended Copy Service operation
To enable a disk for Extended Copy Service operation
1 Install the Hardware Assisted copy license.