How come for me, different RAID stripe sizes = no diff in benchmarks?

[MichaelD]

In AT's recent RAID comparo article, it was shown that HD data transfer rates went up, in step with an increase in stripe size.

In this thread from yesterday, I listed some benchmarks (SANDRA/HDTACH) showing the results of my RAID O array. I was using a 32kb stripe size. It was recommended that I go to a 64kb stripe size. I told you that I would change the stripe size and report back my results.

Well, unfortunately, the results weren't significantly higher. As a matter of fact, you could say the diff would be negligible. Same tests SANDRA and HDTach. I even ran each one twice, just in case.

Now, there's one definite fact that stands: the RAID 0 array's data transfer AND Random Access time is much faster than my single 45GB DM60+ drive. So, overall, I'm pleased that I did it.

I'm just curious why there was little to no difference in performance when changing stripe sizes. I realize this is probably a really deep technical issue that's gonna be over my head, but I want to learn. Thanks.

 

[Vegito]

stripe size almost doesn't show up on benchmarks, my raid controller bios has a stripe size selector, ie it automatically chooses a size for autocad/multimedia, general, spreadsheet/db, etc. I just set mine to general, 32K, if you optimized ur stripe size for certain application, u'll need to run the bench for that app to see the difference...

 

[MichaelD]

Good morning and thanks for the reply. You mentioned something that I've been hoping to get some info on; "optimizing stripe size for application". Well, I don't really have a particular application I use...I just want the fastest load times possible. SCSI is out of my pricerange, else I would've gone that route. Is there a best stripe size for fast load times? Thanks Forcesho.

 

[NelsonMuntz]

I think you should leave it at the highest setting which is what I think you switched it to. Anandtech ran some specialized tests that would run with a lot of different file sizes and stuff like that (if I remember right) to get his benchmarks. Since you are running with the same files (basically) you are not going to show an immediate improvement. As you put more (and larger presumably) files on there you will probably begin to benefit from the larger stripe size.

 

[dkozloski]

32K stripe size works for me. I have a Mylex BT-950 and two Seagate Cheetahs in a RAID 0.

 

[MichaelD]

Thank you, NelsonMuntz; your expertise is greatly appreciated. You are correct; I changed it to a 64kb stripe last night. Do you think a fresh format and OS install would help any? I ghost-copied my old HD to the array. Theoretically, it shouldn't make a diff, but I'm only beginner-level with ghost and it's associated ups and downs. What do you think?

 

[MichaelD]

Dkozloski, did you try other stripe sizes as well? I am brand spanking new to the RAID-thing. I haven't added anything to my HD (info/games/data) and am not opposed to playing around with it somemore.

 

[NelsonMuntz]

You know, I don't think reformatting and reinstalling is going to make any more difference than if you just defragmented. I have a friend that loves to reformat so he does it all the time, but I just don't have the time/energy for that kind of thing. It does keep you on your toes for backing up in case of data loss though.

 

[dkozloski]

I tries 16K and 64K as well as 32K and I couldn't tell the difference. I read that a lot depends on file size. If you have a pretty good mix there is no way to optimize.