IBM ds4800 storage disk port connection and example

I. IBM ds4800 storage disk port connection

The IBM ds4800 storage can connect up to 16 exp100 (SATA) or exp710 (FC). It fully supports the FC and SATA expansion cabinets
Hybrid connection gives users the maximum flexibility. Generally, it is recommended that the expansion cabinet be evenly distributed in four loop pairs when ds4800 is expanded. This will take advantage of the maximum drive-side bandwidth. The ds4800 with a maximum configuration should have four expansion cabinets on each drive-Side Loop pair. Figure-1 shows that a ds4800 has 16 exp710s.

Figure-1 The ds4800 with a maximum configuration has 16 exp710s

Although we recommend that you distribute expansion cabinets to four loops pairs (each loop pair can have up to four expansion cabinets), we still support a loop pair with up to eight expansion cabinets. This means that it is compatible with ds4500 configuration principles (up to two loop pairs are supported ).

Note:In addition to a maximum of eight expansion cabinets in one drive loop pair, another restriction is that two drive loop pairs shared by one drive Channel group can be connected to up to eight expansion cabinets at a time. This means loop pair #1/loop pair #2
The combination cannot have a maximum of 8 exp expansion cabinets. therefore, if you put eight exp expansion cabinets in loop pair #1, you cannot put any exp expansion cabinets in loop pair #2. the same rule applies to loop pair #3 and loop pair #4. if you have 6 exp expansion cabinets in loop pair #3, you cannot put more than 2 exp expansion cabinets in loop pair #4.

Figure-2 ds4500 and exp710s in full Configuration

If you only use ds4800's two drive-Side Loop pairs, instead of all four drive-Side Loop pairs,
It is best to use the following loop pairs: Controller A, port 4/controller B, Port 1 (loop pair
#1); and Controller A, Port 2/controller B, Port 3 (loop pair #3 ).
This will distribute two loop pairs to two Drive channel group pairs. And because they use the separated drive
Channel groups, they do not need to work at the same rate. They can work in either 2 Gbps or 4 Gbps mode.

Figure-3 drive-side connection using loop-pairing methodology

2. Example of connecting the IBM ds4800 storage disk port (drive-side cabling example)

In this example, ds4800 uses all 4 loop pairs, and 16 expansion cabinets are evenly distributed in 4 loop pairs (4 in each loop pairs). For example,-1:

1. From the first expansion cabinet, it belongs to loop pair #1. Connect Controller A, port 4 to the ESM board on the left of the first expansion cabinet.
2. In loop pair #1, use optical fiber cables to connect the out port of the ESM board on the left of the first expansion Cabinet to the in port of the ESM board on the left of the second expansion cabinet.
3. Repeat Step 2 for the 3rd and 4th expansion cabinets in loop pair #1.

4. Use optical fiber cables to connect the out port of the ESM board on the right of the first expansion Cabinet to the in port of the ESM board on the right of the second expansion cabinet.

5. Repeat Step 4 for the 3rd and 4th expansion cabinets in loop pair #1.

6. In loop pair #1, connect Controller A with optical fiber cables, Port 1 to the ESM board's out port on the right of the 4th expansion cabinets, which is the last step to connect loop pair #1.
7. Repeat Step 1-7 (use the next group of drive-Side Loop pair ports), for loop pairs 2, 3, and 4. (Each loop pairs has 4 exp units ).