"Arno Wagner" <(E-Mail Removed)> wrote in message news:(E-Mail Removed)
> Previously Bowser17 <(E-Mail Removed)> wrote:
> > I am wonding what type of increase i will see in a RAID 5 setup using
> > SATA 150 7200 RPM drives vs SATA 150 10K drives (WD Raptors). The
> > raptors are much more expensive than some of the 7200 counterparts,
> > but the access times are much faster.
> Not really.
Uhuh: "So the access time is much faster. Allmost twice as fast."
Babblebot so obsessed with himself.
> WD is of course pretending a huge difference.
But not you, Babblebot: "Allmost twice as fast".
> First, RAID5 does nothing for access times.
Not for the individual drives in it, no.
>
> A typical 7200 rpm drive has 4.1ms access latency.
No babblebot, *all* 7200 rpm drives have an average 4.2 ms latency.
> This time is allways present and is needed after the head seek is complete.
Nonsense. It's an average: based on half a rotation.
And drives can read a number of sectors in the sequence it encounters them first, they don't have to spin to the target sector first
before
they can start reading.
> A 10.000 rom drive has 3ms latency.
>
> As for seek time, it is interesting to see, that sime manufacturers
> (Seagate, e.g. ) do not list it in their drive datasheets anymore.
> I would call that lying.
Corse you would, you are Babblebot.
> Still, from the product manual, average seek for a 7200.10 is 8.5ms
> reading and 10ms writing. For a 10.000 rpm raptor-X, this is 5.2ms
> and 4.6ms. Alltogether 12.6ms/14.1ms vs. 8.2ms/7.6ms.
> So the access time is much faster. Allmost twice as fast.
> As for throughput, the c't magazines "Platten-Karusell" benchmarks
> are very good. RAID with a good and fast controller will multiply
> trhoughput by the number of drives minus one withing limits.
In (simplyfied) theory.
> A 7200.10 500GB drive gets about 60MB/s reading and writing
> on average.
Nope. Thats outerband. The average is (outerband + innerband)/2
For that 7200 innerband is only half of outerband.
> A 150GB Raptor-X gets 73MB/s reading and 72MB/s writing.
Again, outerband. And Storagereview says 88MB/s, 60MB/s innerband.
> This is barely 20% percent more and borderline noticeable.
It will be different for the average: 100.9 48MB/s, Raptor 74MB/s.
And so what. The topic was accesstime.
Random access MB/s will be much lower for the 7200 than for the 10k.
>
> > I would be using these in a standard workstation environment, used for
> > Digital photo editing, programming / development, DVD authoring.
> > I cant see to find a comparison or benchmark specific enough to com-
> > pare different drives in an array, but only how many drives, or diffe-
> > rent RAID controllers. If you can hit me on my email as well as posting
> > to the group, this is my first post, so im not sure if i will get notified.
>
> For any large-file application (photo editing should qualify, DVD
> authoring does qualify) the Raptors are a waste of money. They
> are best in small-access applications, like database access.
> For software development you may experience a moderate speed
> improvement, but I doubt enough to justify the cost. Of course
> some people that allways have to have the fastest solution will
> disagree with this. Personally, I would advise you to go with
> standard drives and invest the money saved in more RAM and
> backup.
>
> Arno
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