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RAID 0 – cluster vs stripe size

with 6 comments

Tired of the heavy NOISE produced by my WD Raptors RAID 0 setup, I’ve decided it was time to move on. Another thing was my little discovery of Seagate’s new enterprise series HDDs – ES.2 with 32MB buffer. I was setting up two powerful gaming rigs for my friends and accidentally found those drives and was thrilled later to test they were actually faster than my Raptors! This was all I needed to make a switch and I’ve bought two 250GB Barracudas for the price of two 74GB Raptors… (well, I’ve paid a fortune for them two years ago but this was my second no-cost upgrade, first was 6600GT AGP for 6800GT PCI-E). Great deal!

This is how I ended up with 500GB damn fast(er) RAID 0 setup, which is quieter, cooler, more energy efficient and with this value for money I’m soon going for a RAID 0+1 setup to makes things right. It’s worth to mention that probably 32MB disk buffer makes the whole difference because side by side single Raptor vs. Barracuda, the latter looks way slower in synthetic benchmarks but this is real life and RAID 0 territory.

Cluster vs Stripe size question

Yeah this is the most interesting part. I’ve made a lot of browsing to understand better how to set up cluster and stripe sizes for my new RAID 0 but strangely I couldn’t find any definite, professional answer. Everybody says it demands on what you need it for, but nobody explains how it really works and the answers are on both far ends. I had a 16KB stripe on my Raptors for all the time, lured by better scores in HD Tach but giving it a second thought they were seeking (noisy) way too much. I wanted to make things right this time and… it turned out that only my logical reasoning was here to back me up and I hope I figured it out properly.

I like the idea of measuring your average file size. I’ve checked various folders like Windows, Programs, whole volumes or my photo storage and settled with a 64KB stripe so Vista/Program files are stripped mostly into three or more pieces and you want at least 2 pieces to use both HDDs equally. Finally 64KB is a maximum size for NTFS cluster, which I used. Why? Nobody explains it but the way I see it stripe size is superior to cluster so, if the smallest file part has 64KB than why strip it to 4KB parts on one disk? Why not “sync” clusters with stripes? I’ve read about “perfect” 4KB cluster and 16KB stripe size but there was no explanation WHY? All I can say is that I have a 1.5GB default sized cluster (4KB) boot partition (Vista want boot/install otherwise), 28.5GB Vista and 435GB storage partition, both with 64KB cluster and it works very well. The disks are quiet but you can hear them at night and I might say they seek less, shorter and less often. I can’t measure the overall performance but it feels snappy as always and HD Tach shows still slightly better scores than Raptors (in HD Tach always the lower stripe the better scores). Files size on disk is generally the same so sixteen times bigger clusters didn’t mess things up which I was afraid of. Probably it would be hard to “loose” significant amount of space. What do you think? Please comment.

Tip of the day

If you want to speed up your computer think about RAID 0 setup instead of expensive CPU/platform upgrade. I have an ordinary AMD dual core 2GHz processor and have no need for anything better. I’ll jump for 4 or 8GB of RAM only to completely turn off page file. RAID 0 gives such a boost to everything you do that every ordinary computer feels like crawling…

seagate-es2

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Written by Hadrys

November 6, 2008 at 22:08

Posted in 7/Vista experience

Tagged with , ,

6 Responses

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  1. You are so right that there are no professional comments on the net. The people only guess in respect of clusters and stripes. But in the end they just write something.

    So I have asked Intel for an explanation. Perhaps I get an answer from there…

    John

    November 19, 2010 at 08:41

  2. […] post is also a reply to John’s comment about […]

  3. You don’t like RAID 0 anymore as I can see.

    I have had it running now for more than 1 year without any problems – 2 TB almost full. And the speed is twice the speed of 1 disk (have 2 disks in the RAID area). Max reading speed is more then 250 MB/s and average is around 230 MB/s. I never want to be without RAID anymore. Sadly you cannot use SSDs for RAID 0 because the TRIM does not work then. Otherwise I would do it.

    In respect of Windows and RAID. Windows does not see RAID at all. For Windows just a disk exists. This is why Windows tools like defragmentation will not work on a RAID disk – just on the logical Windows but not on the HD itself. So you will just defrag the clusters in the Windows disk information but never any data on the disk itself. The RAID controller blocks any software. This is why you do not get SMART data too if you use RAID.

    John

    November 25, 2010 at 04:07

    • I can’t say I don’t like it. I just don’t see the point any more using it in SOHO applications ;)

      In a pumped up workstations it’s obvious to use RAID 0+1 for speed and safety, but in everyday computing I suppose it’s an overkill with HDDs and SSDs available today.

      Currently I simply use an external HDD, which is connected to the PC only during backup so it wan’t fail (storm, physical, wear) and it’s kept in a separate location to protect my data from burglary or fire. Why would you make backup and keep it with your PC ;)

      If this should be done in a professional matter though, I would simply suggest an external network storage device with RAID 1 in a separate location.

      Hadrys

      November 27, 2010 at 21:48

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