RAID Dork

[JohnWeldt]

Hey,

I am new to the raid world and have been reading countless on-line docs and have a few questions.

If I need to increase read/write speed on a drive for large media files what would be the best type? Could you have two RAIDs? Load files on one drive and off load on an other?

To sum it up I need to either increase the drive read/write or separate the drives to push more data thought. My train of thought was RAID0 for performance but then I thought RAID1, I could write to one while reading off the other?

I have a quad encoder that draws more data then the HDD can push out. Any thoughts on how to increase throughput?

Can you have a mixed environment? Raid and normal HDDs?

TYA

 

[JeffD]

John,

Read up on Raid 5. It is the best of both world (speed and reliability). You need a disk controller that supports this mode and at least 3 hard drives.

With 3 drives you get the speed of raid 0, the reliability of raid 1 and only sacrifice the capacity of one of the drives (in raid 1 you also sacrifice the capacity of one drive and get no speed improvement).

Yes you can have multiple disk systems (with and without raid), but Raid 5 is a better solution.

JeffD

 

[chunkymonster]

Not picking on the previous post, just making a statement...RAID5 is a good option, but was meant more for application/file/web servers and generally not best for running an OS. It can be done and I'm sure it would perform well, but that's not what RAID5 was meant for.

Another option could be a RAID 0+1...it would use a total of 4 drives, 2 pairs in a RAID0 then RAID'ed together in a RAID1 array...this would give you the throughput of RAID0 with the redundancy of RAID1.

Here's a link to a RAID tutorial which gives brief descriptions, advantages, and disadvantages of each RAID type.

Good luck!

 

[Codesmith]

Yes you can mix all kind or drives and arrays.

You can have two RAID 0 arrays, one four drive RAID 0, .....

RAID 1 doesn't help read performance in any noticible amout and it cuts write performance in half. Its also extra safe. One drive can die and you lose nothing.

RAID 0 is the very fastest, but when one drive dies all the data is gone forever.

RAID 5 with a real hardware controller is fast and extra safe.

RAID 6 is RAID 5 that can survive two drives dying. If you have lets say 10 or more drives then you might want RAID 6.

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If you need to simply read from or write to a drive really fast then you will want to RAID drives A and B to create a single faster volume.

If on the othe had you need high simultaneous reads and writes then reading and writing to the same volume at the same time is going to cut your performance in half.

In that situation it would be faster to simply read from drive A and write to drive B.

----
More details are necessary.

How much data are we talking about?
Does it need to be protected against hard drive failur?
Is data being read and written at the same time?
What is the minimum read speed you require?
What is the minimum write speed you require?

If the encoder takes raw video data then outputs compressed data then the reads need to be really fast, but the writes don't. If you are going to erase the raw video when you are done, you don't to worry about data safely much. So maybe RAID 0 to a single drive would get the job done.

It all depends.

I recently read about somone setting up a RAID 5 array for a system with a PCI-E 1080p video capture card. It had to be huge and fast to keep up with the cards output. RAID 0 you lose half you capacity with RAID 5 you only lose the capacity of one drive. So RAID 5 was the best choice.

The more details you give the better the advice will be.

 

[RichPLS]

Correction, RAID1 writes are a bit slower than a single drive, but reads are faster than a singe drive...