Sybase IQ supports read-only hardware for both backup and restore operations. The following rules apply:
Sybase IQ prevents writes to a read-only device during restore because the device may be frozen in read-only mode at the hardware level.
Virtual backup will not back up or restore the header block of a read-only dbspace or any other block on a read-only dbspace. Since a read-only dbspace is guaranteed never to change, virtual backup and restore need only restore a read-only dbspace after media failure of the read-only dbspace.
Non-virtual full backup will back up all dbspaces, regardless of mode.
Non-virtual incremental backup will not back up read-only dbspaces that:
Were read-only at the time of the previous backup that the incremental backup depends on,
and
Have not been altered since.
The contents of such dbspaces are wholly contained by a previous depends-on backup. Read-only dbspaces that have been altered since the time of the depends-on backup are backed up.
