[G4] EIDE and Ultra ATA RAID

[shopdog]

How does RAID 10 work, and how many drives to you need minimum?

On Apr 25, 2005, at 4:23 PM, Ralph Garrett wrote:

> Some thoughts on RAID Arrays.
>
> RAID 0, Striping a matched set of drives does not decrease the MTBF 
> for the array, the MTBF remains the same as for a single drive. Loss 
> of a drive in a striped Array does mean you lose all of the data on 
> both drives, but a striped Array can and should be backed up just like 
> any other drive.
>
> RAID 1, Mirrored Arrays are used to increase data security by writing 
> the same data to multiple hard drives, but there is a performance hit 
> on mirrored arrays.
>
> There are several other schemes to improve data security and 
> performance but for the desktop user, probably the best solution is to 
> mirror and stripe, RAID 10, but obviously that's a more expensive 
> solution.
>
> RAID Arrays setup using Disk Utility are called soft RAIDS. The CPU/OS 
> has to manage the RAID so you don't get the performance boost you 
> would with a hardware RAID controller.
>
> The average desktop user won't see much speed improvement by 
> installing a RAID Array but for those who render 3D scenes, edit 
> video/audio files or very large Photoshop files there can be a big 
> improvement in performance. The most cost efficient way to do this is 
> to use a pair of smaller drives (30 to 80 GB's) in a striped array, 
> and use that array as a scratch disk only. If a drive fails in the 
> array, very little critical data is lost and is usually easy to 
> recreate. You also need to be ruthless about clearing files that are 
> no longer needed. I have clients erase the scratch Array after they 
> finish every project so they start with a clean slate.
>
> You can also gain a small performance boost by using drives in a 
> conventional manner attached to multi channel drive controllers, 
> storing the OS on one drive and apps on another drive.
>
> HTH
>
> Ralph
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