Sure, it is done all the time, but you do need to do a START NORECOVERY.

You generally have to shut the system down to "install and cable" the disk to avoid electrical/interface problems. The usual approach is to use SYSGEN to configure the new device on the path where it will reside, keep the new configuration, shutdown the system, install the disc, and do a START NORECOVERY.

Once the disc is recognized by the system, you can add it to your running configuration as follows (assuming the new drive will be LDEV 5 in the system volume set):

:volutil

> newvol mpexl_system_volume_set:member5 5 90 90 (DISC,SPOOL)

[Note: For details, see "Volume Management" or "Performing System Management Tasks" ]

This will add the volume to the system volume set, but it also has some side effects. Since the new volume is "empty" and the disc space allocation routines attempt to "balance" loads across drives, all of your new files and transient space will be allocated on the new drive until it's capacity approaches that of

the other volumes. This will create an I/O bottleneck on that drive, at least initially.

You could selectively :RESTORE certain accounts (or the whole system) to try and balance the allocation. You could also perform an INSTALL and a :RESTORE for better efficiency, but at the cost of a great deal of time. There are also certain 3rd-party utilities that will balance disc utilization across members of a volume set. These utilities work online on a running system and don't require any downtime. [Note: De-Frag/X, from Lund Performance Solutions and Disk Space Manager, from Bradmark Technologies.]