Hp ProLiant DL980 G7 Server Bedienungsanleitung PDF herunterladen (Seite 34)

Figure 31 Setting the Xp_CmdShell option

Analysis Services instance parameters

Flight Recorder

SQL Server Analysis Services Flight Recorder provides a mechanism to record server activity into

a short-term log. Information captured by Flight Recorder can be helpful for troubleshooting specific

issues; however the load placed on the server when capturing the snapshots and trace events can

have a small impact on overall performance. For optimal performance, the flight recorder should

be disabled unless attempting to capture diagnostic information relevant to troubleshooting a

specific problem.

Random File Access

A Boolean property that indicates whether database files and cached files are accessed in random

file access mode. This property is disabled by default. By default, Analysis Services does not set

the random file access flag when opening partition data files for read access. On high-end systems,

particularly those with large memory resources and multiple NUMA nodes, it can be advantageous

to use random file access. In random access mode, Windows bypasses page mapping operations

that read data from disk into the system file cache, thereby lowering contention on the cache.

Available only on SQL 2012 and later.

LowMemoryLimit

Specifies the amount of memory allocated by Analysis Services at startup. When this limit is reached,

the instance starts to slowly clear memory out of caches by closing expired sessions and unloading

unused calculations. The server will not release memory below this limit. The default value is 65,

which indicates the low memory limit is 65% of physical memory or the virtual address space,

whichever is less.

TotalMemoryLimit

Defines a threshold that, when reached, causes the server to deallocate memory more aggressively.

The default value is 80% of physical memory or the virtual address space, whichever is less.

CoordinatorQueryBalancingFactor and CoordinatorQueryBoostPriorityLevel

When multiple users access SQL Server Analysis Services concurrently, an expensive query that

needs to scan large number of partitions can monopolize the system and block other users. To

avoid this problem and achieve high concurrency, HP recommends that

CoordinatorQueryBalancingFactor be set to 1 and CoordinatorQueryBoostPriorityLevel to 0.

EnableRolapDistinctCountOnDataSource

Queries that include DistinctCount in a ROLAP process can run faster, assuming certain criteria

are met. Performance is improved because more of the operation has been off-loaded to the

relational database engine, where COUNT(DISTINCT column) is used to return unique non-null

values, eliminating the need for more expensive ordering operations that degrade query

performance. This optimization is disabled by default because the query results produced by the

34 Using HP ESO

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Hp ProLiant DL980 G7 Server Bedienungsanleitung Seite 34