Windows Disk Alignment Test

The Windows operating system writes data to disk in 64k chucks.  However, Windows Server 2000, 2003 and Windows XP all incorrectly begin writing data at the 63rd sector.  This means the first 1k of the chuck is written into one sector, and the remaining 63k in the next, and so on.  The consequence of this behavior means that for every read and write, two sectors must be accessed from disk instead of one.  This basically doubles your disk I/O. The additional I/O (especially if small) can impact system resources significantly.

Therefore, whenever a Windows host experiences a slowdown, you may want to check the disk alignment to determine whether the slowdown can be attributed to one/more unaligned disk partitions. This test enables you to perform such a check.

This test is disabled by default. To enable the test, go to the enable / disable tests page using the menu sequence : Agents -> Tests -> Enable/Disable, pick the desired Component type, set Performance as the Test type, choose the test from the DISABLED TESTS list, and click on the << button to move the test to the ENABLED TESTS list. Finally, click the Update button.

Target of the test : A Windows host

Agent deploying the test : An internal agent

Outputs of the test : One set of results for each physical disk partition on the Windows host being monitored

Configurable parameters for the test

Parameter	Description
Test Period	How often should the test be executed.
Host	The host for which the test is to be configured.
Detailed Diagnosis	To make diagnosis more efficient and accurate, the eG Enterprise embeds an optional detailed diagnostic capability. With this capability, the eG agents can be configured to run detailed, more elaborate tests as and when specific problems are detected. To enable the detailed diagnosis capability of this test for a particular server, choose the On option. To disable the capability, click on the Off option. The option to selectively enable/disable the detailed diagnosis capability will be available only if the following conditions are fulfilled: The eG manager license should allow the detailed diagnosis capability Both the normal and abnormal frequencies configured for the detailed diagnosis measures should not be 0.

Measurements made by the test

Measurement	Description	Measurement Unit	Interpretation
Disk partition alignment status:	Indicates whether this disk partition is aligned or not.		If the partition is unaligned, this test reports the value Partition is not aligned. For an aligned partition, this test reports the value Partition is aligned. The numeric values that correspond to the above-mentioned measure values are described in the table below: Measure Value Numeric Value Partition is aligned 100 Partition is not aligned 0 Note: By default, this measure reports one of the Measure Values listed in the table above. The graph of this measure however will represent the disk alignment status using the numeric equivalents - 100 or 0. If a partition is found to be misaligned, you can use the detailed diagnosis of this test to figure out the caption, device ID, logical partition name, and block size of the faulty partition.