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Hi does anyone have any input on how a SAS 15k RPM drive would perform compared to a sata based SSD drive, assuming its using the latest verison of sata.

These drives would be in a 4 drive raid 10 configurtion and the sizes are around 70GB per drive.

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    Which SSD drive? There will be a huge difference between your $150 consumer SSD drive and your $10000 enterprise SSD drive.
    – EEAA
    Mar 9, 2011 at 3:46
  • @ErikA I haven't selected any drives yet - I was hoping it would be possible to select some SSD drives that are around 60-75GB and save on cost compared to SAS 15k drives. Do you have any examples of what you consider enterprise level SSDs? What are the main differences between consumer vs enterprise level SSDs? Mar 9, 2011 at 3:53
  • Besides the specific drive, also keep in mind high performance storage systems are far faster than the drives. They do this with features like battery backed memory cache and deduplication. Also drives perform very different based on the type of usage such as large, linear read/write verse small and random read/write.
    – JOTN
    Mar 9, 2011 at 4:05

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Given equivalent sizes, the SSD's will give you vastly more I/O operation performance than the SATAs will.

Both are fast enough to saturate the SATA connection given the right I/O access patterns, though the SSD's will deliver it more often.

As with most performance comparisons, it depends on what you're doing with them. At sizes like these I suspect you're more concerned with throughput than bulk storage. The SSD config will blow the SAS drives out of the water for the lots-of-random-tiny-accesses usage pattern, and you're going to be more constrained on your RAID1 controller (if hardware) or your SATA links.

The big caveat is one ErikA pointed to. The cheapest SSD drives you can get won't do much better than the SAS drives and will most certainly die a lot faster. The more advanced drives will both last longer and withstand more pounding.

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    To put some numbers in: SAS drives: maybe 500 IOPS if you are lucky. SSD: 50.000 are not unheard of. Factor of 100 times faster.
    – TomTom
    Mar 9, 2011 at 4:54
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As mentioned before, it greatly depends on the use of the drives. We for instance have a 200GB database. For queries that need to walk through a full 75GB table, SSD's don't bring a huge performance gain. But when you have some queries that use indexes to do some cherry picking from your hard drive...the SDD's really show a great performance boost. All of this is based on a very basic test setup with consumer grade (fast, less durable) SSD's.

As for the drives you could use. I've been looking to put some Vertex 2 Pro SAS or Vertex 2 EX in our servers. The EX version is supposed be extra durable (and expensive). Vertex has recently launched the Vertex 3 Pro, which is cheaper and much faster, but it uses a relatively new controller that still has to prove itself. You can read a bit about it here: Vertex 3 Pro Review

Hope this helps with your question!

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