On Fri, Sep 11, 2009 at 4:46 PM, Chris Du <dilid...@gmail.com> wrote:
> You can optimize for better IOPS or for transfer speed. NS2 SATA and SAS > share most of the design, but they are still different, cache, interface, > firmware are all different. > > Then by much better, I don't mean just IOPS, it's all the 3, better IOPS, > command queue and error recovery, etc. > And I'm asking you to provide a factual basis for the interface playing any role in IOPS. I know for a fact it has nothing to do with error recovery or command queue. Cache size and type isn't changed based on interface, whoever told you that was selling you beachfront property in Phoenix. It also won't change IOPS because sooner or later you're going to spinning media. It may help with bursty sequential transfers, it will not do a thing for sustained random I/O. Firmware may be different but the only differences there that I've ever seen are to provide the proper intelligence to talk SAS, SATA, or FC respectively. Regardless, I've never seen either one provide any significant change in IOPS. I feel fairly confident stating that within the storage industry there's a pretty well known range of IOPS provided for 7200, 10K, and 15K drives respectively, regardless of interface. You appear to be saying this isn't the case, so I'd like to know what data you're using as a reference point. --Tim
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