RAID5 May Soon Be Obsolete

Justin Kerr

RAID  5 users anxiously awaiting the debut of 2 TB drives to help build massive storage array’s may want to think twice before taking the plunge. An in-depth look into the underlying problems with massive storage RAID5 configurations suggests that s a single drive as redundancy might not cut it anymore. SATA drives carry a specified unrecoverable read rate of 10^14. This might sound like a huge number, but it basically tells us that any array in excess of 11.37 TB will contain at least one unrecoverable read. In the case of a RAID 5 rebuild, this can be catastrophic.

Storage companies want us to believe that RAID 6 will address the issue but sadly this doesn’t seem to be the case long term. The additional drive will increase redundancy, but since failures will always be followed by read errors on another drive, RAID 6 won’t help you one bit (pardon the pun). Many of the advances in storage capacity are a result of perpendicular recording which help reduce this problem, but it still exists. Perpendicular recording also isn’t likely to take us much further beyond 2TB. Delays in finding new methods will force those in need of massive storage configurations to turn to RAID5 or 6 which as we know now, are vulnerable.

Don’t get me wrong, we still have time to come up with a solution to this problem, but users stringing together 6 or more disks as early as next year could start hitting this ceiling. Additionally, in order for the worst case scenario to occur (loss of all data) the one failed drive would need to be completely unrecoverable. So the sky isn’t falling, but it sure makes for an interesting problem. Want to learn more about RAID? Read Maximum PC’s in-depth guide, RAID done Right .

An interesting item of note, on human progress. The picture shown below is just slightly over 2TB of storage . This much capacity will be possible in a single drive by next year. Isn’t progress wonderful?

(Image Credit Rainwulf.com)

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