[Monty Python]

On another forum, they all believe that a RAID 0 (Stripe) has a better data transfer rate than does a single HD by itself, and advocate that it be used as a more cost-effective way to speed up their gaming, than paying big bukcs for a 10,000 RPM Rapter.

I have always believed that a RAID 1 (Mirror) is faster than a single drive, and cannot help but think that it would also be faster than a RAID 0.
As it was explained to me, having the same data written twice allows for faster read times, and having two places to be able to write it frees-up the CPU, etc... to move on to other things, while the RAID Controller Card completes the write operation etc...

I cannot see how removing the advantages of duplicate data on two drives and then doubling the overall (effective) size of the drive AND dividing the data over two different disks is going to result in a performance IMPROVEMENT. It would seem to me to be the opposite; that a RAID 0 ought to be not only slower than a RAID 1, it ought to also be slower than a single drive (non-RAID) all by itself.

So which is correct, and why ?

 

[elf]

Well I've never had the ability to test the speeds, I have always heard that RAID 0 was faster than RAID 1.

Raid 0 allows the computer to read from both drives simoultaneously, while Raid 1 uses the second drive as a backup.

I am not good at explaining this...so here is a link
http://www.mtechlaptops.com/raid.htm

 

[Monty Python]

Re: The Article (Linked)

RAID 0

Characteristics/Advantages

I/O performance is greatly improved by spreading the I/O load across many channels and drives.

RAID 1

Characteristics/Advantages

One Write or two Reads possible per mirrored pair

Twice the Read transaction rate of single disks, same Write transaction rate as single disks

The article makes no comparison between the two relative to speed. It's says performance is "greatly improved" in a RAID 0, but then specifically says RAID 1 has "Twice the Read transaction rate of single disks, same Write transaction rate as single disks."

So okay, either is faster than a "plain old" single HD, but which is faster between the two, and why ?

I'm thinking that it depends on the number of HD's and controllers in the RAID 0, as it said something about best performance being had when there was only one controller per HD, which seems to me that spreading the same amount of data over multiple sources is faster than accessing it from a single source.

Which then sort of implies that the performance of a 3-disk RAID 0 is going to be better than a 2-disk RAID 0.

But what about when comparing (for example) a RAID 0 of 2 - 250 Gbyte HD's in a single stripe to 2 - 500 Gbyte HD's in a RAID 1 (mirror) ?

I'm thinking that the RAID 0 is going to be about 25% faster, because it should have twice the read & write speed of a single drive (as it is able to read & write to two drives simultaneously), while the RAID 1 will have twice the read times, but on 1X write times.

Can anyone confirm this ?

 

[kodi]

http://www.pcguide.com/ref/hdd/perf/raid/levels/comp-c.html

 

[Monty Python]

Thanks. That pretty much confirms my thoughts earlier.