IBM 990 - Manual (Page 107)

Chapter 3. I/O system structure 95
Figure 3-10 16-port ESCON - LIC-CC
An ESCON channel add will never activate the spare channel port. However, if the spare port
on a card was previously used, then the add may activate all the remaining ports on that card.
If there are not enough inactive ports on existing 16-port ESCON cards installed to satisfy the
additional channel order, then IBM manufacturing ships additional 16-port ESCON channel
card(s) and an LIC-CC diskette.
If there has been multiple sparing on a 16-port ESCON card and, by replacing that card the
additional channel add can be satisfied, the card will be replaced.
A maximum of 1024 ESCON ports can be activated on a z990 server. This maximum requires
69 16-port ESCON channel cards to be installed. The z990 model A08 can have up to 720
ESCON ports, on 48 channel cards, which is limited by the number of STIs available on the
A08 model.
16-port ESCON channel sparing
The last ESCON port on a 16-port ESCON channel card (normally J15) is assigned as a
spare port. Should an LIC-CC-enabled ESCON port on the card fail, the spare port is used to
replace it, as shown in Figure 3-11 on page 96.
If the initial first spare port (J15) is already in use and a second LIC-CC-enabled port fails,
then the highest
LIC-CC-protected port (for example, J14) is used to spare the failing port.
L
IC
C
C
E
NABL
E
M
E
N
T
ESCON-16
J00
J01
J02
J03
J04
J05
J06
J07
J08
J09
J10
J11
J12
J13
J14
J15
ESCON-16
SPARE
CHANNEL
J00
J01
J02
J03
J04
J05
J06
J07
J08
J09
J10
J11
J12
J13
J14
J15
ESCON-16
J00
J01
J02
J03
J04
J05
J06
J07
J08
J09
J10
J11
J12
J13
J14
J15
ESCON-16
SPARE
CHANNEL
J00
J01
J02
J03
J04
J05
J06
J07
J08
J09
J10
J11
J12
J13
J14
J15
AD
D
4
ES
CO
N
Ch
an
ne
ls
PCHID
Number
110
111
120
121
110
111
120
121
112
113
122
123