HP ProLiant DL980 G7 Server - Manual (Page 46)

To change the status of an individual trace flag, select a new value from the drop down box and
click SET.
CAUTION: Each trace flag covers a very specific field and requires certain conditions to work.
Caution should be used when turning a trace flag on or off.
Trace flag 8048
Enable trace flag 8048 (TF-8048) to use memory allocation at the CPU level in order to reduce
costs when you have too many CPUs per NUMA node.
Trace flag 834
When combined with the Lock Pages in Memory option described previously, this flag forces the
SQL Server to use 2MB pages for the buffer cache instead of the default 4KB pages. This reduces
the Translation Look aside Buffer (TLB) size and contention, and simplifies memory management
by reducing the number of pages to be tracked and manipulated. This flag is recommended
particularly on systems where the SQL Server is the main (or only) application running.
Trace flag 1117
Trace flag 1117 determines how the SQL Server automatically extends (grows) data files in a file
group when automatic file growth is needed. Enable trace flag 1117 to cause the SQL Server to
automatically grow all of the files at the same time. Otherwise, the files will automatically grow in
round-robin fashion.
Trace flag 1118
Trace flag 1118 is used to help alleviate allocation bitmap contention in tempdb when under a
heavy load of small temp table creation and deletion.
Trace flag 2371
Trace flag 2371 is used to address the well-known problem caused by the current 20% threshold
that determines when automatic statistics updates occur. The statistics keep track of the number of
changes made to a table. The threshold is the percentage of the number of rows in the table. When
the number of changes exceed 20% of the number of rows in the table, the statistics are
automatically updated. For large applications with correspondingly large tables, this could mean
that automatic updates would not occur often enough to accurately reflect current statistics. As a
result, administrators would have to manually update the statistics (using a query plan, for example).
Because the manual updates usually require excessive I/O, this was not optimal for many
applications. The 2371 trace flag changes the threshold from a fixed-rate of 20% to a dynamic
rate based on the table size. The higher the number of rows in the table, the lower the threshold
will become to trigger an update of the statistics. Enable the 2371 trace flag to prevent the need
for manually updating the statistics.
NOTE: To prevent small tables from being updated too frequently, automatic updates require a
minimum of 500 rows in a static table and 6 rows in a temp table.
Trace flag 2549
The DBCC CHECKDB checks the logical and physical integrity of all objects in the specified database.
The command builds an internal list of pages to read per unique disk drive across all database
files. The logic determines unique disk drives based on the drive letter of the physical file name of
each file. If the underlying disks are actually unique when the drive letters are not, the DBCC
CHECKDB
command treats these database files as residing on one disk. Enable the trace flag to
optimize the CHECKDB process by treating each database file as residing on a separate, unique
disk drive. Do not use this trace flag unless you know that each file is based on a unique physical
disk.
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