What does fragmentation do

Best of Techopedia weekly. News and Special Offers occasional. Techopedia Explains Fragmentation. What Does Fragmentation Mean? Techopedia Explains Fragmentation Fragmentation, which happens when the contents of a single file are stored in a non-contiguous space, occurs three forms: Internal fragmentation: Unusable allocated space that reduces performance. Files are stored in clusters, which are mini-allocated hard drive storage areas. Each file is automatically written at the beginning of a cluster, which creates a gap potential between the first and last file bytes, that is, slack space.

Internal fragmentation also occurs when additional specific bytes are allocated to each file for alignment. External fragmentation: Unusable allocated storage space. To resolve this issue, use SQL Defrag Manager to rebuild the indexes to store them in contiguous pages and reduce the need to switch between extents. SQL Defrag Manager is a unique SQL Server index defragmentation solution that automates the time-consuming process of finding index fragmentation in SQL Server based on parameters that you define within a policy for the targeted database.

It gives you the flexibility to reduce the SQL fragmentation immediately or during off-peak hours, all through an easy-to-use graphical user interface. There are no manual scripts required to tackle fragmentation in SQL Server. Join our email list and receive the latest case studies, event updates, product news, and much more. What is Fragmentation?

Understanding the Different Types of Fragmentation There are several types of fragmentation that can occur and impact SQL Server performance and space usage.

File fragmentation at the operating system level When deletes and inserts are performed over time, pages become fragmented as the physical sequence of data pages no longer matches their logical order.

Logical order fragmentation This issue, also known as external fragmentation within SQL Server, is similar to file fragmentation at the operating system level. Page density fragmentation This issue, also known as internal fragmentation, occurs as pages split to make room for information added to a page, there may be excessive free space left on the pages. Fragmentation Examples Imagine there are two data pages for a table with a clustered index.

Defragmenting an Index Example Consider a simplified example of pages after many inserts, updates, and deletes, as shown in the following figure. Sorting is now complete, as all the remaining physical pages match their logical positions.

How SQL Defrag Manager Compacts Data In addition to reordering the leaf pages of the index, SQL Defrag Manager compacts the data in the pages using the original fill factor value specified for the table and then removes any empty pages. Consider the following conditions related to this compaction phase: Compaction is completely skipped if the Inhibit Page Locks property is set for the index.

There are various algorithms built into the compaction phase to stop unnecessary work. For example, if the first page in the index is empty and all the other pages are full, SQL Server does not repeatedly move all the data forward one page.

Disk Defragmenter might take from several minutes to a few hours to finish, depending on the size and degree of fragmentation of your hard disk. You can still use your computer during the defragmentation process. If a disk that you're expecting to see under Current status is not showing up there, it might be because it contains an error.

Try to repair the disk first, then return to Disk Defragmenter to try again. Windows 7 More Network locations can't be defragmented. Need more help? Join the discussion. Was this information helpful? List of Partners vendors. Tim Fisher. VP and General Manager, Lifewire. Tim Fisher has more than 30 years' of professional technology experience.

He's been writing about tech for more than two decades and serves as the VP and General Manager of Lifewire. Facebook Twitter LinkedIn. Updated on March 26, Tweet Share Email. In This Article. What Are File Fragments? Fragmentation: An Analogy. Why Fragmentation Happens. Defragmentation to the Rescue! More on Defragmentation. Was this page helpful? Thanks for letting us know!

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