Before addressing specific examples for the Sample SP Switch System, review the possibilities for frame expansion, and general concerns.
When you add a frame to your system, you can add the frame at the end of your system, between two existing frames, or even at the beginning. A special case of the first two possibilities is a non-switched expansion frame.
In some configurations, a frame might exist that contains nodes and a switch but the nodes do not use up all the switch ports. One or more non-switched expansion frames can be added, immediately following this frame, whose nodes will share the preceding frame's switch.
If you have not planned ahead for other expansion, IBM suggests that you add frames only to the end of your system. Otherwise you will have to reconfigure the SDR, and perhaps have to move nodes to accommodate your needs.
This is fairly straight forward if the frame number was reserved. This is true whether the new frame is a switched or a non-switched expansion frame. However, if the frame number was not reserved, there can be much work to do. The new frame splits the old system into 2 pieces, and the second piece (the higher numbered frames) must be redefined to the system. Further, for a switched system, some amount of recabling will be necessary, prior to the cabling of the new frame to the existing system.
If your system has a switch, the first frame in the system must have a switch. Therefore, if you plan on inserting the additional frame in the first position in your system, that frame must contain a switch.
If your system does not have a switch, you can insert the additional frame in the first position without any such restriction.
Beyond this item, this case has some of the same overhead as the previous case: the entire old system is the "second piece".
The following are topics you need to consider when adding a new frame to your system.
When adding a frame to a system, you need to ensure that the control workstation has enough spare serial ports to support the additional frames. One serial port is required for each additional frame, two for an SP-attached server. If you do not have enough ports, you need to upgrade the control workstation.
If you use HACWS, there are two control workstations to consider.
You need to consider the existing configuration and plan your new configuration by following the rules explained in Understanding placement and numbering. Be careful to not interrupt a switch capsule.
You need to consider what types of nodes you already have and what types you will be adding in the additional frame. For example, consider how thin, wide, and high nodes work together.
You need to consider the implications involved if your system has a switch.
You need to consider the Ethernet network being used. Ask yourself whether you want to separate the Ethernet into multiple subnets. For example, do you want to have one network per frame with one boot-install server per frame or do you want to boot all of the frames from the control workstation?
Also, consider the bandwidth of the default thin wire Ethernet. This Ethernet can load approximately 8 nodes at a time. With larger systems, there are higher technology Ethernets available that can allow you to load software at a faster rate than with the thin wire Ethernet.
Your decision for the previous concern will play a role in planning for IP addresses. You need to ensure that the nodes that will occupy the additional frame will have IP addresses. If you are using a netmask that limits the number of addresses you can have, you can either modify your netmask to free up addresses or you can use a different subnet.
If you have a partitioned switched system, and the new frame is a non-switched expansion frame, you might not need to re-partition, because partitioning for a switched system assumes the maximum number of nodes are present; so the nodes in the non-switched expansion frame are already accommodated. However, at this point you might decide you do not like where the new nodes have implicitly resided, in which case you must re-partition.
If the new frame has its own switch, then you are increasing the number of switches in the system. If your system is partitioned, in this case you will need to re-partition the system because partitioning had not previously accounted for these new nodes.
If you have a partitioned switchless system, you must re-partition, because partitioning in this case is based on the number of nodes actually installed.
Consider Frame 1 of the Sample SP Switch System. It has only 5 nodes so 11 node switch ports are available for other nodes to use. Given Frame 1's configuration, 8 ports are actually set aside for Frame 1 so 8 ports are available for expansion frames. Frame 2 uses only 3, but reserves at least 4. Specifically, Frame 2's nodes are located such that a second expansion frame of 4 nodes is valid. You can insert a Frame 3 with up to 4 nodes and cable all these nodes to Frame 1's switch.
Therefore, you need to accomplish the following:
For the Sample SP Switch System, you could add a Frame 5 which is a non-switched expansion frame for Frame 4. Frame 4's switch has several unused ports and Frame 4 has only 4 nodes located such that Frame 4 can be expanded by as many as 3 frames. So, Frame 5 would be the first of these expansion frames. This expansion would be done like that in Scenario 2-A.
Alternatively, you might want to add a frame after Frame 4 which has its own switch. Given the preceding discussion, you might want to designate the new switched expansion frame as Frame 8 (or 6 or 7). You should do this to reserve space for non-switched expansion frames to come later. This case is more complicated, because you are adding a new switch, thereby changing an important part of the system. The following modifications must be made to the 2-A list:
Suppose you wanted to insert a frame between Frames 1 and 2, where this new frame will also be a non-switched expansion frame to Frame 1. To accomplish this expansion, first delete Frame 2 from the system, then add Frame 2 (the new frame) and Frame 3 (the previous Frame 2) to the system. Note that the old Frame 2 nodes will be rebuilt as Frame 3 nodes. You must: