February 4, 2010 at 11:27 am
Gurus
Can we have MDF and NDF in a different drives with different raid levels. we have a situation where MDF, NDF and LDFs are jumbled on two different drives. Please let me know.
Thanks
Ali
February 4, 2010 at 11:36 am
I'm not a guru but the answer is Yes you can.
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February 4, 2010 at 11:41 am
I thought having mdf and ndf in different drives with different raid levels will cause extra IOs isnt it..correct me if i am wrong!!
i am confused. let's take an example of a million row table with 100 columns. say 90 of them are located in drive A and 10 of them are in Drive B. isn't that a big mess?? I guess my total concept is wrong. but please correct me
Thanks
Ali
February 4, 2010 at 11:51 am
Ali_SQLDBA (2/4/2010)
I thought having mdf and ndf in different drives with different raid levels will cause extra IOs isnt it..
Why?
i am confused. let's take an example of a million row table with 100 columns. say 90 of them are located in drive A and 10 of them are in Drive B. isn't that a big mess??
Columns aren't split across files, rows are. If you have a million row table with 100 columns and two files you could have 600 000 rows (all 100 column) in one file and 400 000 rows (all columns) on the other data file.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
February 4, 2010 at 11:56 am
GilaMonster (2/4/2010)
Ali_SQLDBA (2/4/2010)
I thought having mdf and ndf in different drives with different raid levels will cause extra IOs isnt it..Why?
that was because of space issues with the original MDF Drive... however, we are currently running with few on raid 10, few on raid 5 including LDFs on these drives. So, is it really recommendable to have MDFs and NDFs on different drives. Please make me understand.
Thanks
Ali
February 4, 2010 at 12:01 pm
Ali_SQLDBA (2/4/2010)
GilaMonster (2/4/2010)
Ali_SQLDBA (2/4/2010)
I thought having mdf and ndf in different drives with different raid levels will cause extra IOs isnt it..Why?
that was because of space issues with the original MDF Drive... however, we are currently running with few on raid 10, few on raid 5 including LDFs on these drives. So, is it really recommendable to have MDFs and NDFs on different drives. Please make me understand.
No, I was asking why you think that having files on different drives causes extra IOs.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
February 4, 2010 at 12:06 pm
Because, SQL tries to look at different drives, and pull data from different drives which indicates more IOs (May be i am completely wrong!! correct me if I am)
Ali
February 4, 2010 at 12:18 pm
Ali_SQLDBA (2/4/2010)
Because, SQL tries to look at different drives, and pull data from different drives which indicates more IOs
What's the difference between pulling 50MB of data from one drive and 40MB of data from a second drive versus pulling 90MB from a single drive?
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
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