RAID configurations for data recovery in SQL Server

From a simple standpoint, not everyone is employing every single technology listed above. From a hardware redundancy standpoint most servers come with multiple power supplies and multiple network cards, but what about all of the rest of the items. The next line of defense is usually with the RAID configuration. In low to mid tier servers, there is usually one controller card and some type of RAID configuration associated with it. As for the database perspective most servers are probably set up to use RAID 1, RAID 5, RAID 10 or some combination of these.

Understanding RAID
RAID (redundant array of independent disks) levels come in many different variations. The most common are:

There are many more RAID configurations available. Some are practical and some are not. Some only exist on certain vendor products. To learn more, read this article about different RAID levels.

Selecting a RAID configuration
When setting up SQL Server, there is no option that checks the RAID configuration type being used, and likewise there are no recommendations on what to use. Most of what you will read often points to the need to have some time of disk redundancy. But as far as what to use – RAID 1, 5 or 10 – this is pretty much left up to the server administrator or the DBA to figure out.

In the good old days when disks were small and RAID t

Digg This!     StumbleUpon     Del.icio.us

RELATED CONTENT SQL Server Backup and Recovery The keys to database backup protection for SQL Server Choosing a SQL Server disaster recovery solution Licensing a standby server for SQL Server replication Can I encrypt and restore a database backup in SQL Server 2005? SQL Server errors, failures and other problems fixed from the trenches Get SQL Server log shipping functionality without Enterprise Edition SQL Server 2008 backup compression pros and cons SQL Server backups using SAN database snapshots Tips for scheduling and testing SQL Server backups Code to restore SQL Server databases in VB.NET SQL Server Backup and Recovery Research SQL Server High Availability, Scalability and Reliability Top load balancing methods for SQL Server Maintaining high availability of SQL Server virtual machines Creating fault-tolerant SQL Server installations Scaling up vs. scaling out with SQL Server 2008 How to configure storage in SQL Server database with more writes than reads SQL Server database replication tutorial Licensing a standby server for SQL Server replication Get SQL Server log shipping functionality without Enterprise Edition Monitor database mirroring and replication after a SQL Server upgrade Upgrade live applications to SQL Server 2005 for high availability SQL Server High Availability, Scalability and Reliability Research SQL Server Replication Top load balancing methods for SQL Server New replication features in SQL Server 2008 and what they mean to you SQL Server database replication tutorial Licensing a standby server for SQL Server replication Upgrade live applications to SQL Server 2005 for high availability Tool to synchronize two SQL Server databases Simplify SQL Server replication Replication techniques in SQL Server Podcast: SQL Server high availability options Managing identity columns with replication in SQL Server

RELATED GLOSSARY TERMS Terms from Whatis.com − the technology online dictionary rollback  (SearchSQLServer.com)

RELATED RESOURCES 2020software.com, trial software downloads for accounting software, ERP software, CRM software and business software systems Search Bitpipe.com for the latest white papers and business webcasts Whatis.com, the online computer dictionary

echnology was not as advanced, the process of getting the best throughput was to have as many disks as possible and to spread your I/O over these disks using multiple filegroups. This is still the case today. But with faster drives, faster controllers and larger capacity drives the configurations are much less complex then they were. Also, when you consider the continued growth of centralized storage systems, much of the control of setting up and maintaining RAID configurations is put in the hands of the storage administrator and not in the DBAs.

So what needs to be done from a recovery perspective?
As mentioned above, SQL Server doesn't know what type of RAID configuration your system is utilizing, so from a recovery standpoint there is no difference when recovering a database on a RAID 0, 1, 5 or 10 array. The one difference you will probably notice is the time it takes to restore the database. As mentioned above there is a level of write speed depending on the type of RAID configuration. Other than the speed of the restore there is not much else that needs to be done from a DBA perspective.

The advantage of using a RAID configuration providing data redundancy is the potential to avoid the need to restore your database. With the use of hot swappable drives or spare drives if there is a disk failure, your system should be able to rebuild the array while the database stays online. Therefore the potential for any data loss is eliminated. That said, it is still important to take backups of your database, because you never know if there could be a complete failure of the RAID array, the server or your data center.

Summary
Although SQL Server does not recommend or really care what type of RAID configuration you are using, you want to make sure you're covered from a disk failure. Select a RAID configuration that provides the data security, but also make sure you have a backup process in place in case there ever is a complete failure. With continued advances in hardware and redundant components you would think you could get away with not doing backups. For the most part this is probably true, but don't get caught without your backups in the event of a bigger catastrophe.

[TABLE]

Rate this Tip To rate tips, you must be a member of SearchSQLServer.com. Register now to start rating these tips. Log in if you are already a member. DISCLAIMER: Our Tips Exchange is a forum for you to share technical advice and expertise with your peers and to learn from other enterprise IT professionals. TechTarget provides the infrastructure to facilitate this sharing of information. However, we cannot guarantee the accuracy or validity of the material submitted. You agree that your use of the Ask The Expert services and your reliance on any questions, answers, information or other materials received through this Web site is at your own risk.