You can mix DIMMs of different rank counts, subject to the configuration rules described below. Memory modes The HS21 XM supports three mutually-exclusive memory modes: normal, mirroring, and sparing. Normal Flat Mode The full capacity of all DIMMs is available to the operating system, however, no hot-spare or memory mirroring capabilities. Configuration rules: The above installation sequence applies. DIMMs 5 and 7 must match. DIMMs 3 and 1 must match.
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You can mix DIMMs of different rank counts, subject to the configuration rules described below. Memory modes The HS21 XM supports three mutually-exclusive memory modes: normal, mirroring, and sparing.
Normal Flat Mode The full capacity of all DIMMs is available to the operating system, however, no hot-spare or memory mirroring capabilities. Configuration rules: The above installation sequence applies. DIMMs 5 and 7 must match. DIMMs 3 and 1 must match. DIMMs 6 and 8 must match.
Memory mirroring Mirroring Mode In mirroring mode, the server maintains two identical copies of all data in memory. In the event of an uncorrectable error in one of the copies, the system can retrieve the mirrored copy of the data. The use of memory mirroring means that only half of the installed memory is available to the operating system. DIMMs 1, 3, 6, and 8 top row labelled Slot 1 must match. The top row and bottom row of DIMMs do not have to match. Hot spare memory Sparing Mode This mode provides a degree of memory redundancy but not to the extent of memory mirroring.
It also leaves relatively more memory to the operating system than mirroring. In sparing mode, the trigger for fail-over is a preset threshold of correctable errors.
When this threshold is reached for an active memory rank, the content of that rank is copied to the spare rank. The failed rank of memory is taken offline, and the spare rank is put online and used as active memory in place of the failed rank. The memory set aside for the spare memory is one rank per channel. Configuration rules: DIMMs must be installed in matched pairs and in the same installation order as described above.
All DIMMs in a row slot 0 or slot 1 must match. For example, if you have four DIMMs installed in sockets 2, 4, 5, and 7 , they must be identical. Both DIMMs in a channel must be either single-rank or dual-rank and cannot be mixed. The rank set aside for sparing will be the largest sized rank.
Figure 3 shows four example configurations Example 1 - 4 that are supported. Figure 3. Examples show supported memory sparing configurations Note: The examples in Figure 3 Examples 1 - 4 show that a specific rank is reserved for sparing. This is for illustrative purposes and is not meant to indicate that the rank that is the greatest distance from the controller is the rank that is always used.
Figure 4 shows Example 5 and Example 6, which are configurations that are not supported. Figure 4. Example 5 and Example 6 show memory configurations that are not supported.
Related product families.
Two PowerXCell 8i processors at 3. It ran the Sun Solaris operating system from Sun Microsystems. It also provides outside connectivity via an Infiniband 4x DDR adapter. This makes a total width of four slots for a single TriBlade. To use the other switch module bays, a daughtercard needs to be installed on each blade that needs it, to provide the required SAN , Ethernet, InfiniBand or Myrinet function. Mixing of different type daughtercards in the same BladeCenter chassis is not allowed.
IBM HS21 - BladeCenter - 8853 User Manual