Horst Herb wrote:
A common misunderstanding.
Hyperthreading is of no use (even counterproductive) for database
applications.
Database applications are generally *not* processor intensive (unless
re-indexing etc), but memory intensive.
If you create *virtual* additional processors that try to access memory at the
same time , all you do is hog the bus bandwidth and slow all processes down
at the same time while waiting for memory access.
Just compare real world performance on an machine without looking at the
number of real or virtual processors used - run real world queries from real
world clients simultaneously and measure time until results returned. Both
MSSQL and Firebird will nowadays come close to the limits of your network
capacity even in GB networks without coming anywhere near saturating
processor capacity in nearly any conceivable real world situation unless the
table structure/indices/queries have designed in mindbogglingly stupid ways.
But Firebird will always use only a fraction of the resources MSSQL requires,
and hence be faster on equal machines as long as the machines are not vastly
overdimensioned for the task in which case MSSQL might have a minimal
advantage.
Btw, you will find that with most applications you will gain performance when
switching off hyperthreading - HT is just a marketing gimmick for the
gullible which only has advantage in very specific multitasking situations
that do not require (much) bus access
Behaviour of the server on multiple real processors is a different issue -
mostly dependent on the underlying operating system. Like networking, SMP was
always an afterthought in MS operating systems, carelessly bolted on, so no
wonder that applications benefit little unless specifically optimized for
SMP.
Which kind of leaves in a quandry.
I am trying to spec up a Xen box. It will run two debian guests and
three Windows guests. MSSQL will be the database server on Windows and
MySQL on linux. The MSSQL will be the machine working the hardest,
although I will need at least a gig of RAM for one of the linux vboxen.
Horst, what would you recommend in terms of CPUs (2 or 4?),
hyperthreading (turned off?), RAM (8 gig?), 32 or 64 bit for this
configuration. Anything else I should consider?
David
--
"What do you want to cripple today?"
http://www.microsoft.com/sql/prodinfo/features/compare-features.mspx
"At Microsoft, we believe that software should provide you with choices
that let you find the solution best tailored to your business’ needs."
_______________________________________________
Gpcg_talk mailing list
[email protected]
http://ozdocit.org/cgi-bin/mailman/listinfo/gpcg_talk
