Configuring and Migrating Memory on vPars

18
Memory Migration Management
This chapter describes the tools available to the system administrator to manage and monitor memory
migration before, during, and after the operation. Following are some of the tools available to the
system administrator to manage and monitor memory migration:
• vparstatus command output (-v and -A options).
• GlancePlus performance monitor (gpm –rpt MemoryReport).
• EVM(5) event management progress logs.
• Cancel operation in the vparmodify command (-C option).
The following sections describe in detail when and how these tools can be used. The last section in
this chapter demonstrates the usage of these tools through an example memory migration operation.
Tools to Determine Memory Usage
Before adding or removing memory from the partition, it is critical for the system administrator to
determine the memory usage in the partition. The memory usage on a live partition can be
determined using GlancePlus reporting tool. The GlancePlus has two memory related reports –
MemoryReport and MemoryUsageGraph. The example detailed in the last section of this chapter uses
MemoryReport. The MemoryReport lists the amount of memory free (Free Mem), amount of memory
used by the kernel (Sys Mem) and user (User Mem) and amount of memory used by buffer and file
cache (Buf Cache and FileCache). The report also indicates whether pages are getting swapped to
disk (Paged Out) which is the case when system is low on free memory. MemoryUsageGraph depicts
similar information in graphical form.
Before issuing the command to delete memory from live partition:
1. Find the amount of floating memory the partition has in each locality using vparstatus (-v or
–M option). The amount selected from each locality to delete should be less than or equal to this
amount.
2. Find the amount of free memory (Free Mem) in the partition using GlancePlus (gpm –rpt
MemoryReport). If the amount being deleted is less than free memory, skip the rest of the steps
below.
3. Find the current file cache size (FileCache) using GlancePlus (gpm –rpt MemoryReport).
4. Find the minimum file cache size (kctune filecache_min filecache_max).
5. Add the free memory from step 2 to the current file cache size from step 3 and subtract the
minimum file cache size from step 4 to determine the amount of freeable memory.
6. If the memory being deleted is more than the amount calculated in step 5, reduce the amount to
delete to less than or equal to that amount.
Before issuing the command to add memory to live partition:
1. Find out the amount of free memory in the partition using GlancePlus (gpm –rpt
MemoryReport) and then decide on the amount to add.