SQL Clone
SQLServerCentral is supported by Redgate
 
Log in  ::  Register  ::  Not logged in
 
 
 


Optimizing SQL Server Performance by using File and Filegroups


Optimizing SQL Server Performance by using File and Filegroups

Author
Message
achigrik
achigrik
Valued Member
Valued Member (64 reputation)Valued Member (64 reputation)Valued Member (64 reputation)Valued Member (64 reputation)Valued Member (64 reputation)Valued Member (64 reputation)Valued Member (64 reputation)Valued Member (64 reputation)

Group: General Forum Members
Points: 64 Visits: 1
Comments posted to this topic are about the content posted at http://www.sqlservercentral.com/columnists/achigrik/fileoptimtips.asp



datorres88
datorres88
Grasshopper
Grasshopper (11 reputation)Grasshopper (11 reputation)Grasshopper (11 reputation)Grasshopper (11 reputation)Grasshopper (11 reputation)Grasshopper (11 reputation)Grasshopper (11 reputation)Grasshopper (11 reputation)

Group: General Forum Members
Points: 11 Visits: 1
This article, like many others on the topic, seems to perpetuate a very common misconception regarding the use of multiple files and filegroups.

The misconception is that there is no performance benefit to creating multiple files on the same disk or array. This is simply not true. SQL Server creates a single I/O thread per physical file. With only one data file, there is no way to have SQL Server perform parallel reads. It can be seen by watching disk queue length in perfmon, that often when it appears that SQL Server is I/O bound, the physical disk queue is often very low or even zero. This occurs because SQL Server is bound by the fact that it is only reading data through a single I/O thread and therefore not taking advantage of all the physical I/O bandwidth provided by the disk subsystem. The solution is to create multiple files and use filegroups to place objects on other files to ensure parallel reads.

Also, the argument that separating indexes is a bad idea because it does not allow you to backup a table as a unit is really an inadequate argument. By separating indexes and table data on separate filegroups you speed up the processing of bookmark lookups when a non-clustered index is used. In the 7 years I've been doing database consulting, I have yet to see anyone really use the feature of filegroup backup. Usually, anyone who would need to backup the database in parts is already at the point where they are employing other fault tolerance techniques such as BCV's.



jenningse
jenningse
Mr or Mrs. 500
Mr or Mrs. 500 (598 reputation)Mr or Mrs. 500 (598 reputation)Mr or Mrs. 500 (598 reputation)Mr or Mrs. 500 (598 reputation)Mr or Mrs. 500 (598 reputation)Mr or Mrs. 500 (598 reputation)Mr or Mrs. 500 (598 reputation)Mr or Mrs. 500 (598 reputation)

Group: General Forum Members
Points: 598 Visits: 73
From MSDN -

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnsql2k/html/thestorageengine.asp?frame=true%5d

"Note In SQL Server 2000, the number of asynchronous I/Os is now managed dynamically inside the database engine, and is not influenced by the number of files or filegroups used, as was the case in SQL Server 7.0. "

Have you found this behavior to be different than stated?

[url][/url]



Go


Permissions

You can't post new topics.
You can't post topic replies.
You can't post new polls.
You can't post replies to polls.
You can't edit your own topics.
You can't delete your own topics.
You can't edit other topics.
You can't delete other topics.
You can't edit your own posts.
You can't edit other posts.
You can't delete your own posts.
You can't delete other posts.
You can't post events.
You can't edit your own events.
You can't edit other events.
You can't delete your own events.
You can't delete other events.
You can't send private messages.
You can't send emails.
You can read topics.
You can't vote in polls.
You can't upload attachments.
You can download attachments.
You can't post HTML code.
You can't edit HTML code.
You can't post IFCode.
You can't post JavaScript.
You can post emoticons.
You can't post or upload images.

Select a forum

































































































































































SQLServerCentral


Search