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How much impact does hard drive cache have on IO performance

Are there any statistics or performance tests available that can tell me if there is a difference is 16MB vs 32MB Cache?

If it matters, I am looking at SATAII 7200RPM Drives.

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It would probably do you just as much good to google for "<model number> review". Or look through tomshardware.com. –  Ernie Aug 10 '09 at 18:53
Too many variables to take into account, including the size and other geometry of the drives. –  Karl Katzke Aug 10 '09 at 18:54
He might more generally mean, "How much impact does hard drive cache have on IO performance", and just add the disk details in case that matters. –  Kyle Brandt Aug 10 '09 at 19:07
@Kyle: Yes, you are right. –  Jason Aug 10 '09 at 19:23
@Jason: Perhaps it's a good idea to edit the question then. :) –  Ernie Aug 10 '09 at 19:40

4 Answers 4

up vote 6 down vote accepted

Hasn't this question been asked before?

Basically if you're doing lots of reads from a 17-32Mb data set and have no local cache then it'll make a difference - for everything else you might see a 1-2% overall increase in performance but you're also doubling the chance that in the event of a power loss your disk integrity is lost as the cache isn't battery-backed.

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Thanks... it doesn't look I should go out of my way for a 32MB drive over a 16MB drive. That is what I wanted to know. –  Jason Aug 10 '09 at 19:24

I would pay attention more to performance reviews of hard drives of the same size and rotational speeds (7200, 10000). I have not seen the same series of hard drive manufactored in 2 different cache versions. There is normaly other performance improvements beyond a cache increase in higher end models that make them faster. It is not the cache alone that could make that big of difference.

I would not go out of your way to get a 32mb cache version unless you wanted the higher performance models, which generaly come with higher cache memory already.

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In the IDE days you could often choose between 8 or 16mb cache. I think it was like a $10 price difference... –  Mark Henderson Aug 10 '09 at 21:43
You are correct, they did a little in the past, but I tried to stay focused on the current market. –  Troggy Aug 10 '09 at 22:56

not really. if you want real performance boosts, look at ssd.

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And a massive increase in cost for a 500 GB drive... –  Ernie Aug 10 '09 at 19:39

Caching algorithms, latency, areal density, etc., will all impact your performance--in some cases, they might affect performance even more than the actual cache size. You need to look at benchmarks for various hard drives in the application you're considering.

You can find some good benchmarks here: http://www.storagereview.com

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I think it's worth adding that hard drives will inevitably fail. If possible, you should should try to find a drive in the same price range with a longer warranty period. Over the past several years, warranties have fluctuated between 1, 3, and 5 years. Certain brands give better warranties, but in my experience every brand seems to have about an equal failure rate. –  rob Aug 10 '09 at 20:24

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