number of dump threads controls the number of threads that SAP ASE spawns to perform a memory dump.
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Summary Information |
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|---|---|
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Default value |
Disabled |
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Range of values |
1 (disabled, no parallelism) – 8 (fully parallel) |
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Status |
Dynamic |
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Display level |
Intermediate |
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Required role |
System administrator |
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Configuration group |
Group Diagnostics |
Using the appropriate value for number of dump threads can reduce the amount of time the engines are halted during the memory dump.
Use a value of 8 if the machine has enough free memory for the file system cache to hold the entire memory dump.
If you do not know whether the machine has enough free memory, the value for number of dump threads depends on many factors, including the speed of the I/O system, the speed of the disks, the controller’s cache, whether the dump file lives in a logical volume manager created on several disks, and so on.
Disable parallel processing (by assigning a value of 1) if you do not halt the engines when performing memory dumps, described below.
When SAP ASE performs a memory dump, the number of files it creates is the sum of the number of memory segments that it has allocated multiplied by the number of threads configured. SAP ASE uses separate threads to write on separate files. When this job completes, the engines are restarted, and the files are merged into the target dump file. Because of this, the time to dump the shared memory in parallel is greater than doing it serially.
If you halt the engines during the memory dump, using a value other than 1 may reduce the amount of time the engines spend stopped while dumping the memory.