Raid 0 and Stripe Sets are Risky

RAID 0 or Stripe sets allow two or more physical disk drives to be logically combined so that they appear as single large drive to the operating system. When disk drives are configured as stripe sets or RAID 0, each byte of data is distributed across the available disks. This results in enhanced read performance. The speed in which a single physical disk drive can retrieve and deliver data to the computer is limited by mechanical factors such as how fast the disk is spinning and how fast the heads can move (seek time). When the data is striped across multiple physical disk drives, the logic in the controller can request that each drive return parts of the data simultaneously. The controller can then assemble the parts and deliver the data to the requester faster than it could have been retrieved from a single drive.

RAID 0 is attractive because of it's performance advantages and also because there is no disk space overhead as there is in higher RAID levels like RAID1 and RAID5. However, RAID0 offers no fault tolerance as found in RAID1 and RAID5. RAID1 and RAID5 require extra physical disk drives to store data redundantly so that if one drive fails the data remains available.

Configuration guides and manuals make it clear that RAID0 does not offer fault tolerance, but they don't make it clear that your data is significantly MORE VULNERABLE on a RAID0 or stripe set configuration than a single drive. The reason for this increased vulnerability is because if any one of the drives in the array fail, all of the data on all of the drives will be lost. Let's say a particular disk drive has a 1 in 10 probability of failing in the next 12 months, if your dependent on two of those drives, then your risk of data loss increases to 2 in 10. If your data were dependent on three of those drives, then your risk of data loss increases to 3 in 10. So the more drives you have in your stripe set or RAID0 configuration the higher the probability that your data will be lost. Once again, because each byte of data is striped across all of the drives, the loss will encompass all of the data on all of the drives.

There are some good reasons to configure RAID0 and simple stripe sets, but never for data that cannot be easily and quickly recreated. Temporary files generated and used by applications, databases and operating systems are usually good choices for RAID0 and simple stripe set configurations. Any data that needs to be retained or would be costly to regenerate should not be stored on a RAID0 or stripe set configuration. Although, fault tolerant RAID levels significantly reduces the chances of losing data due to hard disk failure, it is still prudent backup important data and store it offsite.

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