Online spare memory – HP ProLiant ML570 G4 Server User Manual
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Hardware options installation 45
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If multiple hot-add operations are performed, allow one board insertion operation to complete
(as indicated by the memory board LEDs and OS logs) before inserting another memory board.
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If a memory board (which contains DIMMs) is unlocked while in Advanced ECC mode, audio alarms
and visual alerts occur.
CAUTION: When the memory board locking switch is unlocked in a mode that does not support hot-add or
hot-replace capabilities, audio alarms and visual alerts occur. Removing the memory board at this point
causes server failure.
To end the audio alarms and visual alerts, move the memory board locking switch back to the locked position.
This action does not result in data corruption or server failure.
If removal of a single memory board is required and it is the only memory board, power down the server and
make the necessary memory changes.
Online spare memory
Online Spare Memory provides a higher level of memory protection than Advanced ECC. With Online
Spare Memory, the probability of a server failing because of uncorrectable memory errors is reduced.
In this mode, memory that is receiving a high rate of correctable memory errors is automatically
disengaged and a replacement set of memory is used in its place. Since DIMMs that are receiving a high
rate of correctable memory errors have an increased probability of receiving an uncorrectable memory
error (which results in a server failure), the server experiences higher availability. The degraded memory
can be replaced during scheduled downtime and poses no additional risk to the server.
Online Spare Memory is supported with one to four memory boards installed. On this server, each
installed memory board is protected by its own spare memory. No OS support is required.
The following guidelines apply to Online Spare Memory:
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All general memory requirements apply ("
Memory board LEDs and components
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Online Spare Memory is supported with 1, 2, 3, or 4 memory boards.
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Each board must have a valid Online Spare configuration. No dependencies exist for the
configuration between different memory boards.
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Each memory board includes its own Online Spare Bank. All boards operate independently in
Online Spare mode. Each board can failover to its Online Spare Bank independent of the other
memory boards. Some boards can be in Online Spare degraded mode while others are still in
operational Online Spare mode.
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The minimum valid Online Spare configuration for a memory board requires at least one bank of
dual-rank DIMMs or two banks of single-rank DIMMs ("
If the server does not meet these requirements, an error message is displayed during POST and the
server defaults to Advanced ECC and Advanced ECC guidelines apply.
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The server automatically configures the optimal Online Spare solution.
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Online Spare Memory does not support any hot-plug operations.
HP recommends the following configurations. These configurations result in optimal use of memory. Other
configurations are valid, but do not result in the maximum amount of installed memory being available to
the OS.
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If only single-rank DIMMs are used on a memory board, all DIMMs should be of the same size on
that memory board.
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If only dual-rank DIMMs are used on a memory board, all DIMMs should be of the same size on that
memory board.
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If a mixture of single- and dual-rank DIMMs are used on a memory board, the dual-rank DIMMs
should be two times the size of any single-rank DIMM.