On Sat, Sep 12, 2009 at 10:17 AM, Damjan Perenic < damjan.pere...@guest.arnes.si> wrote:
> 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 > The two *'s leave much room to be desired. Averaged? How about some real numbers with testing methodology. I'm not at all surprised they claim 2x performance from the drive they charge twice as much for. On the flip side, according to storage review, the SATA version trumps the SAS version in pretty much everything but throughput (which is still negligible). http://www.storagereview.com/php/benchmark/suite_v4.php?typeID=10&testbedID=4&osID=6&raidconfigID=1&numDrives=1&devID_0=354&devID_1=362&devCnt=2 --Tim
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