SQL Server and R.A.I.D (redundant array of independent disks)

RAID as it was defined initially as Redundant array of inexpensive disks, later RAID Manufacturers reinvented the term as Redundant array of independent disks, which is more appropriate.

Quick review of the RAID’s in use across majority of SQL Server Environments are:

RAID 0 = disk striping. Data (file) is divided into blocks and spread across the raid array in fixed order.

RAID 1 = disk mirroring. Maintains identical copies of Data on Mirrored disks sets. (Excellent redundancy)

RAID 5 = striping with parity. Data is stripped into large blocks and spread across the raid array in fixed order and Data redundancy is provided by the parity information. (Excellent Read performance)

RAID (1+0) 10 = mirroring with striping. RAID 10 uses a striped array of disks which are then mirrored to another identical set of striped disks (Excellent performance & excellent redundancy) ## mostly write

This was a basic overview of the Diff type’s of RAID technologies available. There are also others, beyond the scope of this discussion and beyond of what i have worked in.

What is the best approach for a SQL Server RAID Design or Rather, the Best Plan for SQL Server Data Files Placement.

Some Industry Best Practices for SQL Server Data File Storage are Actually it is mostly a personal choice based on the budget available to sysadmins and DBA’s)

Put the Transaction Log file and Data Files on Separate Set of Disks (R.A.I.D sets)

My most preferred configuration will be a RAID 10 set, which provides excellent performance and excellent redundancy.
RAID 5 is an excellent secondary Option, which provides excellent READ performance, but incase if one of the disks fail, the read performance will degrade a bit.

I know this is a debatable topic, but yes, which topic on any subject is not debatable?. so it depends on your personal environment and choice, keeping in mind the uptime and performance enhancement of your environment, after all you will not want your users to complain of a slow environment or one that crashes frequently.