Bruce Evans wrote:
On Mon, 3 Oct 2005, [ISO-8859-1] Tulio Guimar�es da Silva wrote:
But just to clear out some questions...
1) Maxtor�s full specifications for Diamond Max+ 9 Series refers to
maximum *sustained* transfer rates of 37MB/s and 67MB/s for "ID" and
"OD", respectively (though I couldn�d find exactly what it means, I
deduced that represents the rates for center- and border-parts of the
disk - please correct me if I�m wrong), then your tests show you�re
getting the best out of it ;) ;
much slower.
Another interesting point is that you can often get closer to the maximum
rate than the average of the maximum and minumum rate. The outer tracks
contain more sectors (about 67/37 times as many with the above spec), so
the average rate over all sectors is larger than average of the max and
min,
significantly so since 67/37 is a fairly large fraction. Also, you can
often partition disks to put less-often accessed stuff in the slow parts.
[All GEOM alligning deleted]
As it so happens, I have again some (faster) spare servers in my office.
And given the NFS-tests of last year, I want to see if I could run those
tests again. But before doing so I wanted to verify the extent of what Bruce
suggest here above. (Which I found first in an article some time ago)
I've written a small, not yet complete page, on the topic. At current it only
involves writting to the disk. But it clearly visualises the effect of
non-constant transferrates, which actually depends on the location of the
track read from.
If you want, you could see for yourself at:
http://withagen.dyndns.org/FreeBSD/Performance/Raw-disk/
Suggestions etc. are welcome.
--WjW
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