94 lines
6.4 KiB
HTML
94 lines
6.4 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<meta name="DC.Title" content="Logical partition concept: memory" />
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<meta name="abstract" content="Processors use memory to temporarily hold information." />
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<title>Logical partition concept: memory</title>
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</head>
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<body id="rzaitmainstore"><a name="rzaitmainstore"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Logical partition concept: memory</h1>
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<div><p>Processors use memory to temporarily hold information.</p>
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<p>Memory requirements for partitions are dependent on partition configuration,
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I/O resources assigned, and applications used. When you create a partition,
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you must add a whole number of megabytes of memory to it (1 MB = 1024 x 1024
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bytes). The primary partition needs a minimum of 256 MB of memory. Depending
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on configuration values used, a primary partition may require more than 256
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MB. Secondary partitions running V4R4 and V4R5 require a minimum value of
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64MB. Secondary partitions running V5R1 and V5R2 require a minimum of 128
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MB of memory. Depending on configuration values used, a secondary partition
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may require more than 128 MB.</p>
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<p>Memory in each logical partition operates within its assigned minimum and
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maximum values. You can dynamically move memory between V5R1 and V5R2 logical
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partitions without needing to restart the affected partitions as long as your
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request for memory movement is within the range of the minimum and maximum
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values specified during partition creation. When you request to dynamically
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move memory between partitions, note that this memory is removed and added
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to the base memory pool of each of the partitions (*BASE pool). Private memory
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pools or shared memory pools are not affected. If the move request exceeds
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the amount of memory available in the base pool, the system will only free
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up excess memory pages after keeping the minimum amount of memory required
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in the base pool. This value is determined by the base storage minimum size
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(QBASPOOL) system value. To prevent any data loss during memory movement,
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the system first writes any data from memory pages to the disks before making
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the memory pages available to another partition. Depending on the amount of
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memory you have requested to move, this may take some time.</p>
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<p>Each partition will report its runtime minimum memory size. This value
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is an estimate of how much memory in the partition is locked into that partition
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and cannot be moved dynamically. Reducing the number of processes or threads
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within a partition or changing the *BASE pool will affect the runtime minimum.</p>
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<p>The full amount of memory that you assign to a logical partition may not
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be available for the partition's use. Static memory overhead required to support
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the assigned maximum memory will affect the reserved or hidden memory amount.
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This static memory overhead will also influence the minimum memory size of
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a partition.</p>
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<p>The minimum memory size assigned to a partition can be changed with only
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a restart of the partition. However, changes to the maximum memory size require
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a restart of the entire system and may require a larger minimum memory value.</p>
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<p>If there is a memory failure, the system will attempt to accommodate the
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minimums for all partitions. If all minimums are satisfied, the secondary
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partitions will restart with all additional resources distributed proportionally
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to their allocation. If all minimums are not satisfied, the system will put
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all resources in the primary and fail to restart with the partition configuration
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protected and a product activity log (PAL) error of B6005343. You can view
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memory errors in the PAL on the primary partition.</p>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzaithardwarereq.htm" title="Understand the basic hardware concepts and requirements to partition your server.">Hardware for logical partitions</a></div>
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</div>
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<div class="relconcepts"><strong>Related concepts</strong><br />
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<div><a href="rzaitbus.htm" title="A bus is a conductor that is used for transmitting signals or power.">Logical partition concept: bus</a></div>
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<div><a href="rzaitprocessor.htm" title="A processor is a device that executes programmed instructions.">Logical partition concept: Processor</a></div>
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<div><a href="rzaitwronofflpar.htm" title="Understand how to safely restart and power down a system with logical partitions.">Restart and power down a system with logical partitions</a></div>
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</div>
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<div class="reltasks"><strong>Related tasks</strong><br />
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<div><a href="rzaitpal.htm" title="Use Dedicated Service Tools (DST) or System Service Tools (SST) to find system reference codes for logical partitions.">View the Product Activity Log (PAL) for logical partitions</a></div>
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</div>
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</div>
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</body>
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</html>
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