HP CD-ROM Server User's Guide

A-8 Troubleshooting
Problems When Accessing Disc Changers
Note ❏
Disc changers, with up to 8 discs each, are supported. Up to
56 CD-ROM discs are supported through LUN (Logical Unit
Number) addressing.
The CD-ROM server has a parameter,
JukeBoxLockTime
, which
sets how long a user has exclusive access to a CD-ROM during a
data-read operation. This is to prevent disc-changer flutter in
order to optimize access speed when many users are accessing
different discs in the same changer.
Disc-changer flutter can occur if a user requests access to a
CD-ROM when another user is already reading data from a
different CD-ROM. The changer may then attempt to service
both requests by repeatedly changing between the two
CD-ROMs and transferring a small amount of data each time.
Because of the relatively long time needed to change CD-ROMs,
the data transfer rate to both users will become unacceptably
low.
The
JukeBoxLockTime
parameter will ensure that when there
are simultaneous requests for access to different CD-ROMs, a
sizable block of data is transferred to each user before the
CD-ROM access is changed.
• If the
JukeBoxLockTime
parameter is set too low the data
transfer rate will be unacceptably low.
• If the
JukeBoxLockTime
is set too high the CD-ROM drive
will time-out on a second user’s request before the first
user’s access is completed. This will result in users receiving
a ‘CD-ROM not available’ notice.
The default setting is 0 seconds which disables this function; you
can adjust this value by following the instructions given in
chapter 5.
hp.book Page 8 Thursday, April 2, 1998 4:33 PM