Which Level is best for
RAID Data Recovery?

RAID data recovery can be a complicated process. There are several decisions that need to be made when deciding on what RAID Level to choose. Some levels make recovery easier while others can make it considerably more difficult. We will take a quick look at the question of "which level is best for RAID Data Recovery?"

The mere use of RAID does not protect you against unrecoverable data loss. Even if you use RAID, it is still prudent to consider using a backup strategy. Some RAID configurations are designed to protect you from the loss of a single hard drive. But there are other components that can also cause data loss such as the disk controller. In addition, user error or virus attacks may also lead to data loss. This is why even a RAID set should have a backup plan when mission-critical data is involved.

RAID Levels

Choosing a RAID level requires you to make a decision on disk performance, data reliability, and cost. In general, spending more money, will make it less likely that you will experience a data loss or significant system downtime. The following RAID levels are the ones most commonly used.

RAID 0 - Striping

RAID 0 offers high performance with no fault tolerance. The basic idea with this level is to take two or more disks and combine them to appear as one large disk to the OS. Whenever the user writes a file to the disk, the file is split into pieces and portions of it are sent to each of the disks in the RAID set. This means that each disk has only a part of any one file. This increases performance because the write time is also divided among the disks such that a file is written more quickly then if it were written to one disk alone. The same performance improvement is also realized when reading the file back from the set.

This is not really a true RAID because it is not fault-tolerant. It is missing the redundant component of the RAID acronym. Striping works best with any application requiring high bandwidth such as video production and editing. It is not advisable to use RAID 0 for mission-critical data.

RAID 1 - Mirroring

Mirroring offers high reliability because all files are written to a pair of disks so that each disk has a complete copy of every file. A RAID 1 set must have a minimum of two disks and if using more drives they must be added in pairs such that there are always an even number of disks. All writes to this set are written to at least two disks.

This RAID configuration will protect you against any single hard disk failure. The drawback is that your hardware costs will double because you will have to duplicate all of your hard disk drives. The benefit is that when a single hard drive fails, RAID data recovery is just a simple matter of replacing the broken drive and copying your data from the other dive in the pair.

RAID 5 - Striping with Parity

The RAID 5 set is the most popular application of RAID technology. This requires a minimum of 3 disks for a basic implementation or a minimum of 4 disks if you want a hot-spare. This level uses striping to write a single file over several disks and a parity disk to help recover from the loss of any single disk. Using a hot-spare will prevent downtime if any single disk fails and significantly ease the process of RAID data recovery.

When any single disk fails, a recovery involves replacing the broken drive with a new drive and starting the controller to do a rebuild. The rebuild operation uses the parity information to recover the data from the lost disk. If the RAID set includes a hot-spare, then the controller will do this operation automatically without having to take the disks offline.

Conclusion

Doing a RAID data recovery can be more troublesome because there are new ways that a set can fail than if your data simply resided on a single disk. A RAID 0 set will not protect you against data loss but it will give you better performance. By building a RAID 5 set, you can protect yourself from the failure of any single hard disk and avoid the labor costs of system downtime. You will also avoid the cost of sending a broken hard drive to a recovery service to get your lost data back. For the best protection, a backup strategy can be combined with a RAID set.

Return from RAID Data Recovery to Data Recovery