Re: iSeries Disk Pricing

[Syd Nicholson <sydnic@xxxxxxxxxx>]

On PC based servers the data base is often located on a single disk. If one
has an SQL server database, the entire database is usually installed on one
single DASD. At best, a PC data base can only serve one user at a time, all
other users must join the queue.

On the iSeries, with data spread over multiple disks this limitation does not
apply. An iSeries should easily out perform any equivalent PC database server.
The number of disk arms in this situation is extremely important.

It is not unusual for PC DB servers to run like a dog unless very fast drives,
powerful CPUs, extra memory for caching, etc, etc is present. Many companies,
including those that develop these PC systems, just don't realize the
implications of scale. That which works perfectly in a test environment,
performs abysmally, or dies when put in the real environment because the
system is unable to handle the load. This is where the iSeries wins and
Windows based systems fail.

The iSeries has the advantage of scalability and stability, and the number of
disk arms is part of this equation. Whether a PC DB has 10 users, or 10,000
users it cannot go any faster by adding more CPU power, or memory if the rate
limiting factor is how fast it gets data from a single disk. Overload it and
it dies, and probably the network with it with devices timing out all over the
place.

Syd Nicholson




>
> > Subject: RE: iSeries Disk Pricing
> >
> > This is a multipart message in MIME format.
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> > Everybody keeps chanting the arms mantra as if a bank of original 10mb
> IBM
> > PC hard drives would out perform a 8gb iSeries drive.  I argue that if
> > they keep improving all of the other performance metrics of drives
> then
> > you may not need as many arms for the same amount of data.
> >
> > Rob Berendt