Hitachi 1000 Advanced ECC, Online Spare Memory, Online spare memory supported configurations

Advanced ECC

Conventional ECC is intended to correct 1-bit errors and detect 2-bit errors. Advanced ECC, also known as Chipkill, corrects up to four or eight bits of an error that occurs in a DRAM installed on a

x4- DRAM or x8-DRAM type DIMM, respectively. Accordingly, the system can operate normally even if one DRAM fails, as illustrated in Figure 14.

Figure 14. Advanced ECC

Online Spare Memory

Online spare memory provides the functionality to switch over to spare memory if correctable errors frequently occur. This function is enabled to prevent system downtime caused by a memory fault.

BladeSymphony 1000 supports the online spare memory function in the ten patterns of memory configurations listed in Table 5. The shaded sections represent spare banks. Online spare memory excludes the use of the memory mirroring function.

Table 5: Online spare memory supported configurations

Bank	Bank1		Bank2		Bank3			Bank4
Slot	Slot 1	Slot 2	Slot 3	Slot 4	Slot 5	Slot 6		Slot 7	Slot 8
Configuration 1	2 GB	2 GB	2 GB	2 GB	2 GB	2 GB		2 GB	2 GB
Configuration 2	1 GB	1 GB	1 GB	1 GB	1 GB	1 GB		1 GB	1 GB
Configuration 3	512	512	512 MB	512	512 MB	512		512	512
	MB	MB		MB		MB		MB	MB
Configuration 4	2 GB	2 GB	2 GB	2 GB	2 GB	2	GB	None	None
Configuration 5	1 GB	1 GB	1 GB	1 GB	1 GB	1	GB	None	None
Configuration 6	512	512	512 MB	512	512 MB	512		None	None
	MB	MB		MB		MB

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