Inventec B800, Руководство пользователя

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Hardware Operations
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2.5.1 System Memory Organization Modes
The Romley-EP/EP 4S platform supports four different memory RAS modes:
Independent Channel Mode, Rank Sparing Mode, Mirrored Channel Mode, and Lockstep
Channel Mode. The rules on channel population and channel matching vary by the RAS
mode used. Regardless of RAS mode, the requirements for populating within a channel
given in Section 6.3.2 must be met at all times. Note that support of RAS modes that
require matching DIMM population between channels (Mirroring and Lockstep) require
that ECC DIMMs be populated. Independent Channel Mode is the only mode that
supports non-ECC DIMMs in addition to ECC DIMMs.
For RAS modes that require matching populations, the same slot positions across
channels must hold the same DIMM type with regards to size and organization. DIMM
timings do not have to match but timings will be set to support all DIMMs populated
(i.e., DIMMs with slower timings will force faster DIMMs to the slower common timing
modes).
Independent Channel Mode
Channels can be populated in any order in Independent Channel Mode. All four
channels may be populated in any order and have no matching requirements. All
channels must run at the same interface frequency but individual channels may run at
different DIMM timings (RAS latency, CAS latency, and so forth).
Rank Sparing Mode
In Rank Sparing Mode, one rank is a spare of the other ranks on the same channel. The
spare rank is held in reserve and is not available as system memory. The spare rank
must have identical or larger memory capacity than all the other ranks (sparing source
ranks) on the same channel. After sparing, the sparing source rank will be lost.
Mirrored Channel Mode
In Mirrored Channel Mode, the memory contents are mirrored between Channel 0 and
Channel 1 and also between Channel 2 and Channel 3. As a result of the mirroring, the
total physical memory available to the system is half of what is populated. Mirrored
Channel Mode requires that Channel 0 and Channel 1, and Channel 2 and Channel 3
must be populated identically with regards to size and organization. DIMM slot
populations within a channel do not have to be identical but the same DIMM slot
location across Channel 0 and Channel 1 and across Channel 2 and Channel 3 must be
populated the same.
Lockstep Channel Mode
In Lockstep Channel Mode, each memory access is a 128-bit data access that spans
Channel 0 and Channel 1, and Channel 2 and Channel 3. Lockstep Channel mode is the
only RAS mode that allows SDDC for x8 devices. Lockstep Channel Mode requires that