Overview of the storage structure design and appearance of IBM ds4800

I. IBM ds4800-framework (chassis) Design

The basic controller unit of the IBM ds4800 storage is divided into five main fru (field replacement units) components.
These components are two control modules, two control support modules, and one
Interconnect module.

Figure-1 ds4800-Framework Design

· These controllers include XOR engines, processors, and another electronic device used to process I/O.
· The Controller support modules include power supplies and fans.
· The interconnect module contains battery and hot swappable midplane modules.
All five FRUs are hot-swappable and can be replaced online, allowing ds4800 users to maximize online time.

In terms of the composition and appearance of FRUs, The ds4800 architecture is significantly different from the previous ds4000 architecture. If you compare the ds4800 and ds4500 frameworks (chassis), you will find significant differences.

· The Controller of ds4800 is located behind the Controller Unit, while the controller of ds4500 is located at the front.
· The ds4800 host-side connection and drive-side connection are now integrated into the controller, instead of the ds4500 on the separated minihubs.
· The cache backup battery is now in the interconnect module.
· Midplane is currently hot-swappable and is located inside the interconnect module.
· The fan and power supply are inside the Controller support module and are located at the front of ds4800.
By reducing the number of FRUs, ds4800 helps simplify the tasks of managing and maintaining basic controller units.

Figure-2 ds4500 framework (chassis) Design

Ii. IBM ds4800-front

The front of ds4800 consists of two controller support modules and the interconnect module.

The two controller support modules are the units (FRUs) on the left and right respectively ). each of them contains a fan and a 375 W power supply. to replace the fan and power supply, you need to unplug the Controller support module and then replace the faulty part.

The interconnect module is a unit (FRU) located between two controller support modules ). The interconnect module contains cache battery and new hot swappable midplane. When the interconnect module is unplugged, ds4800 automatically suspends controller B, switches all logical volumes (Luns) to Controller A, and continues working.
Note:When the interconnect module is unplugged, although the ds4800 automatically suspends controller B and switches all Luns to Controller A, it is recommended that the interconnect module be removed before, first, manually switch all the Luns to Controller A, and put controller B in the offline status.

When the interconnect module is restored to its original position, ds4800 will return to normal working status. However, you must manually re-allocate Luns to their respective controllers (A or B) Because ds4800 will not automatically do the work for you.
All marked parts are hot-swappable and can be replaced online, so as not to cause user downtime.

Figure-3 front of ds4800

3. interconnect module and battery pack)

The interconnect module provides an electronic communication path between the power supply and the fan, allowing their power supply to load-share and charge the cache backup battery pack. It contains two cache backup batteries. Each battery pack contains a battery used for two controller caches.

Figure-4 ds4800 interconnect Module

The ds4800 battery pack has no expiration date. When a problem occurs in a battery pack through LEDs, you only need to replace the battery pack without having to replace the two battery packs at the same time. When any backup battery pack fails, the write cache will be disabled. Therefore, you should replace the faulty battery pack as soon as possible to minimize the impact caused by the write cache being disabled.

Iv. IBM ds4800-Rear

Ds4800 rear, two controllers stacked up and down. Controller A is at the top, controller B is at the bottom, and their orientation is reversed. The Controller is hot-swappable. Each controller has two Ethernet RJ45 interfaces and one serial port (Serial Port .)