IBM 450 xSeries, Planning And Installation Manual

Page: 35 / 160

Chapter 1. Technical description
21
Memory mirroring, Chipkill, and Memory ProteXion provide multiple levels of
redundancy to the memory subsystem. Combining Chipkill with Memory
ProteXion enables up to two memory chip failures per memory port (14 DIMMs)
on the x450. An x450 with its two memory ports could sustain up to four memory
chip failures. Memory mirroring provides additional protection with the ability to
continue operations with memory module failures.
1. The first failure detected by the Chipkill algorithm on each port doesn’t
generate a light path diagnostics error, since Memory ProteXion recovers
from the problem automatically.
2. Each memory port could then sustain a second chip failure without shutting
down.
3. Provided that memory mirroring is enabled, the third chip failure on that port
would send the alert and take the DIMM offline, but keep the system running
out of the redundant memory bank.
1.8 PCI subsystem
As shown in Figure 1-12 on page 22, there are six PCI-X slots internal to the
x450:
򐂰 Two 133 MHz slots, which accept 32-bit or 64-bit, 3.3 V, PCI or PCI-X
adapters, from 33-133 MHz
򐂰 Two 100 MHz slots, which accept 32-bit or 64-bit, 3.3 V, PCI or PCI-X
adapters, from 33-100 MHz
򐂰 Two 66 MHz slots, which accept 32-bit or 64-bit, 3.3 V, 33 or 66 MHz, PCI or
PCI-X adapters