disk i/o structures specifies the initial number of disk I/O control blocks SAP ASE allocates at start-up.
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Summary Information |
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|---|---|
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Default value |
256 |
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Range of values |
0–2147483647 |
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Status |
Dynamic |
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Display level |
Comprehensive |
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Required role |
System administrator |
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Configuration group |
Disk I/O, Memory Use |
User processes require a disk I/O control block before SAP ASE can initiate an I/O request for the process. The memory for disk I/O control blocks is preallocated when SAP ASE starts. To minimize the chance of running out of disk I/O structures, you should configure disk i/o structures to as high a value as your operating system allows. See your operating system documentation for information on concurrent disk I/Os.
Use sp_sysmon to determine whether to allocate more disk I/O structures. See Performance and Tuning Series: Monitoring SAP Adaptive Server with sp_sysmon. You can set the max async i/os per server configuration parameter to the same value as disk i/o structures.