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I'm going to be rebuilding my server, and I want much faster access to my data. I've used RAID 1 and 0 in the past, and decided upon RAID 10 (dedicated RAID card). Then someone told me to use RAID 5+0, then someone else told me to use RAID 6+0.

Assuming the Hardware RAID Card supports each level, what is currently the FASTEST RAID available, given x number of hard drives? Reliability is now another factor, and I am willing to spend money on new drives if a drive (or multiple) fail. I simply want to know what the fastest RAID level is, along with some reliability for recovering from a failure

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Could you clarify your edit? What do you mean by "reliability" - fault ride-through? Longevity? It contradicts your earlier requirement that "reliability is not the main factor". Also, can you describe which parts of the Wikipedia page for RAID that are confusing and that don't answer your question? –  sblair Jun 16 '12 at 4:36
@sblair Done edit –  Canadian Luke Jun 16 '12 at 7:07
While their are differences between the various levels you can usually see a much bigger difference by simply adding more spindles and making damn sure you have a RAID controller with a largeish battery backed cache so your OS/software simply pushes writes to controller memory, and the controller can push them to disk when the I/O load permits it. –  Zoredache Jun 17 '12 at 9:59
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closed as not constructive by DragonLord, techie007, Canadian Luke, Nifle, Oliver Salzburg Jun 30 '12 at 21:45

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1 Answer

up vote 3 down vote accepted

The fastest (and unsafest) RAID is striping aka RAID 0.

If you are going to use that make sure you have backups.

[Edit: added stuff below]

A very brief RAID summary:

  • RAID 0: Split data across several drives. FAST! If one drive fails then you lose all data.
  • RAID 1: Write all data to multiple drives. Not faster when writing. Optionally faster when reading since you can read from several disks at one. You lose a lot of disk capacity (if using 2 drives one of them is a copy of the other, so two 1TB drives yield 1TB of space. If you go extra secure with three copies you have 1/3th total usable space etc).
    • RAID 10: Combine at least 4 drives in two pairs. Forming a stripe of mirrors or a mirror of stripes. Used when both speed and safety are needed. You lose half of the disk space.
  • RAID 5: Ok when reading. Slower when writing. Advantage: you loose only one disk of capacity. Fine when mostly reading and storing large amounts of data. You loose 1 drive of capacity. You can loose one hard drive without losing any data.
  • RAID 6: Same as RAID 5 with two drives of capacity lost. You can lose two hard drives without using data. Maybe slower than RAID 5 when writing because of non-trivial parity calculations.

If you want maximum speed: Use SSDs and put them in a stripe. But keep backups of important data.

You should always keep backups of all data, a RAID is not a backup. Not even a RAID6.

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If you use a RAID0 from X drives, and even one of them fails you loose your data. With more drives you gain more speed, and increase the risk of failure. –  Hennes Jun 16 '12 at 0:01
Evidence? Aren't you here because you're looking for people with expertise? –  OmnipotentEntity Jun 16 '12 at 4:17
@OmnipotentEntity You're right... But unfortunately, not everything on the Internet is true, so asking for evidence (which may be the wrong word) is just me wanting to see real-world evidence, instead of just theoretical answers. I do NOT mean to sound rude, but in hind sight, I may have come off that way, so I do apologize –  Canadian Luke Jun 16 '12 at 7:09
Just to repeat what OmnipotentEntity already added: Backups, backups, backups. Also there is not backup except an off-site backup. And untested backup might be useless. –  Hennes Jun 16 '12 at 11:14
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