Yet another question on the ideal RAID stripe size

[AluminumStudios]

I'm sure this has been discussed before, but a search didn't turn up much ...

I have an Epox 8k3a+ with the Highpoint 372 IDE RAID controller. I want to stripe together two WD400bb 40 gig drives into RAID 0 for video capture, editing, and rendering (and to reduce my drive letters!)

I'm going to mainly be working with large files from 100 megs to 2 gigs. So I assume a larger than default stripe size would work for me ... but how large? The default is 64 kb. With a 2 gig file that's a lot of bloody stipes ^_^; I was thinking of 256 kb just because I don't know how a 512 or 1024 kb stripe would work.

I don't care at all if I don't get a performance boost on small files. It's the 100 meg+ ones that I"m concerned about.

So any opinoins on what stripe size I should use?

 

[VezZiE]

Once I read from a site that says 16k performs better (I set mine to it, and no performance problem so far). But I forgot what the site is, he actually compare and benchmarked all the results. I'll post a follow up once I found it back..

 

[NOX]

Well, I have mine at 64kb, and everything runs very fast. Not sure what the advantage would be if you went smaller or bigger?

 

[Bovinicus]

I just did a little bit of research, and it seems as though larger stripe sizes increase write performance more than other stripe sizes. Also, larger stripe sizes are in fact better for large files. 512KB seems to be the optimal one. You posed a good question; I like when answering a question requires me to learn something. =)

 

[GT1999]

Well, I don't get good RAID-0 performance no matter what on my Highpoint 374, and I don't know why. The best performance by far though is with 16k.

512K stripe = 32,000 avg. in HDTach
16K stripe = 46,000 avg. in HDTach

This is with 2x WD 800JB in RAID-0 both on their own channels and IDE cables, 80-pin.

Now, just ONE of the 800JBs gets 40k even in HDTach. It's also much more consistant than having the two hooked up in RAID-0 (reads are much more even and don't go down to 5k sometimes, ie dips in performance). Though it's only 10% CPU utilization for RAID-0 compared to 4% without, I don't like the dipping in performance.

Anyway, go with 16k

 

[Bovinicus]

Geekish, for the average user 16K is a good stripe size. That is indeed true. However, he is NOT the average user. He deals with files with sizes of up to 2GB, which are written and read better with larger stripe sizes. Trust me, I just did a lot of research on the subject.

 

[technogeeky]

Hmm.

What about for me?

I have an Abit IT7 with the HPT 384 controller, I think.

I just bought a 2nd WD 120 JB drive to RAID-0 it with my current drive.

I move a lot of MP3's around, a lot of large files (movies), and I play some games too.

 

[RanDum72]

The best stripe sizes, as far as benchmarking is concerned (from HDTack to Sisoft sandra) is 16-32k for Highpoint controllers. The only advantage when using large strip sizes is when using large files such as video editing where throughput is more consistent. Under HDTach, strip sizes above 64k usually show lower overall throughput but is usually almost a straight line, with less dips and spikes.

 

[smp]

scenario:

You move a 2 gig file ... 16k stripe size
The controller has to break that 2 gig file into 2gig/16k (you get the picture, lots and lots of writes are gonna happen)

You move a 2 gig file ... 512 stripe sizes
The controller has to break the 2 gig less, lowering the overhead, decreasing the amount of writes that are happening .. better

You move a < 1 meg file
The controller doesn't break the file into two big pieces, each one is written ... perfomance not so great cause you're not doing much striping

Bigger files sizes .. bigger stripes
Smaller file sizes .. smaller stripes

There is no general rule, as some people claim in this thread.
It's all relevant as others are pointing out.

 

[AluminumStudios]

Thanks for the responses.

I'm using 256 kb stripe but I think I"ll bump it up even more. For 2 gig files the difference between 16, 32, 64 and even 128kb seems pretty insignifcant. And what SMP said was true and a big eye opener - 2 gigs with a 16 kb stripe = approx 161,000 chunks!
There's gotta be some mad overhead induced by that.

A typical operation for me is to capture video (stream write large files) and render from Premeiere and After Effects (where the app reads from a lot of large files, and continuously writes a new large file.)

I haven't run any scientific tests yet, but at 256 kb it doesn't feel much faster than individual drives.

I'm not just looking for speed though. My individual drives were workable as they were. Another reason for RAID was to reduce the number of drive letters I had and consolidate my space.