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SQL RAID Setup recomendations

Hi guys,

Looking for some feedback on the best raid setup for an SQL database we will be migrating.  I procured a new Dell R720 Server with 64GB RAM  / two 8 core Xeon 2.9ghz Processors with 6 15K SAS drives 600GB a piece.

Originally I went with using 5 drives in a RAID-5 array with a hot-spare configured.  Then I started second guessing myself about the need to keep transaction logs separate on different physical disks in-case of the worst case scenario.  RAID-5 will allow me 1 drive failure, and the added hot-spare.  But Should I be considering using a RAID-10 setup?  This is a school lunch program used by 4 schools so not heavily intensive, but I'm more concerned about backups, and data integrity.

Or should I do 2 drives as my OS and hosting the SQL Server in a RAID-1 configuration, and then use the remaining 4 as my second drive letter in a RAID-10 configuration housing my transaction logs?  Lot's of options, and each has its pros/cons.  Anyone care to offer their expertise/opinion?
1 Solution
Dan CraciunIT ConsultantCommented:
I use the following setup:
1. system partition (C:): Raid1, 2 drives
2. data (MDF) partition (D:): Raid1, 2 drives
3. log partition (E:): Raid1, 2 drives
4. TempDB partition (F:): no Raid, 1 drive
5. 1 drive kept in a drawer, as spare.

Fairly intensive db usage, working for 3 years, survived 3 dead hdd's.

by far the best i have used is raid1 2 drives, (best performance is gained when 2 independent raid controllers are used)

this is used for operating system only

use raid 10 for the data base

Following are the key points to remember for raid 10.
    if possible use additional raid controllers for added performance
    Minimum 4 drives. (in addition to the 2 used for your OS)
    This is also called as “stripe of mirrors”
    Excellent redundancy ( as blocks are mirrored )
    Excellent performance ( as blocks are striped )
    If you can afford the dollar, this is the BEST option for any mission critical applications (especially databases).

drives dont cost nearly as much as they used to in real terms and the performance gainesmake the initial investment worth it
As you have 6 disks i would go with:
OS- raid 1, 2 disks
SQL data - raid 1,  2 disks
Just SQL transactional logs - raid 1,  2 disks

Another option is to combine OS and SQL data on raid10 and keep trans. logs on raid1.
But I would keed OS and SQL data on different partitions. (In case SQL data grows too much the OS will still have enough space to function normally, so you can focus only on SQL problem)

transactional logs should be on separate raid 1 because of performance, as writing to logs is sequential. And also it is more secures as they are located an different drives as SQL data.
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Raid 10 needs 4 disks to function properly, so that would be 8 disks
NoodlesWIUAuthor Commented:
@QuinnDex - I have 6 disks.  If I did a RAID-10 it would be 4 disks in that configuration for logs and the other 2 in a RAID-1 for the OS Volume.
NoodlesWIUAuthor Commented:
I have 1 RAID controller and initially planned on using the hardware as a Virtual-Server in a RAID-5 with Hot-Spare.  Still toying with keeping it that way.  Many Pros and cons to each setup RAID wise.
you was looking for feedback on the best.. thats what i gave, you can still do the raid 1 OS raid 10 db with 6 disks and 1 controller, it will still give you the best performance.

extra controllers will only increase the performance they dont change the best configuration
NoodlesWIUAuthor Commented:
@Quindex - I greatly appreciate the feedback.  I was just trying to clarify that I still could do RAID-4 just would need to use 4 for that and 2 for a RAID-1.  How is the performance with OS in RAID-1 for a database applications?
the database application would be on the raid 10,  not on the raid 1 with the os,

if you put the database on the raid 1 with the os you would run into o/i read/write problems and as your database load grows so will they
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