On Sat, Sep 12, 2009 at 7:25 AM, Tim Cook <t...@cook.ms> wrote: > > > 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. > > 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. > > 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.
I shopped for 1TB 7200rpm drives recently and I noticed Seagate Barracude ES.2 has 1TB version with SATA and SAS interface. In their datasheet at http://www.seagate.com/www/en-us/products/servers/barracuda_es/ and product overview they claim following: --- Choose SAS for the seamless Tier 2 enterprise experience, with improved data integrity and a 135 percent average performance boost over SATA. SAS also reduces integration complexity and optimizes system performance for rich media, reference data storage and enterprise backup applications. --- With a choice of either SATA or SAS interfaces, the Barracuda ES.2 drive utilizes perpendicular recording technology to deliver the industry’s highest-capacity 4-platter drive. SAS delivers up to a 38 percent IOPS/watt improvement over SATA. --- And in Product overview: --- • Full internal IOEDC/IOECC* data integrity protection on SAS models • Dual-ported, multi-initiator SAS provides full-duplex compatibility and a 135 percent average** performance improvement over SATA. *IOEDC/IOECC on SATA (writes only), IOEDC/IOECC on SAS (both reads and writes) **Averaged from random/sequential, read/write activities with write cache off -- I admit I have no clue why SAS version should be/is faster. I just pass on things I found out. But I am interested in opinion if there is any substance in this marketing material. Kind regards, Damjan _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
