Scott Lindstrom schrieb:
Since you can only have 8 drives on a 515, the only constraint would
have be memory.
What are "they" recommending for a box ?
What does this application do and what is the primary language ?
Pat-
The box is being quoted at 3gb of memory. The app is JD Edwards World
(English).
If 3gb is not enough RAM to get the rated CPW, I wonder what is?
The BP recommends an M25 series box.
Scott
Hello Scott,
CPW Measures are ALWAYS meant for the system being fully equipped with
every disk, memory and cache controller you can put in.
BUT: The i5-515 is a special one, as is the 510-M15. These machines are
politically constrained, which means that you cannot use the full CPU-Power
if you are running I/O intensive jobs on them. The good news is, that
there is
no more "Hypervisor job" artificially contorlling how much power you can
get.
There is a note in the Redpaper about these new systems an I think your BP
is referring to that:
Note 1: The Model 515 provides full processor power (batch or 5250 OLTP)
for applications that are not I/O intensive. For applications
that are I/O intensive, this translates to approximately 800 CPW (batch
or 5250 OLTP) for either the 1-way or 2-way because the Model
515 has a maximum of eight disk drives. CPW is used to compare relative
performance rating among processor models within the IBM
System i family.
As a reminder, do not use CPW as the sole metric for sizing workloads on
any IBM System i model. Additional considerations include
disk I/O-per-second rates and application workload attributes. As a
starting point for disk I/Os per second on the Model 515, consider a
maximum of approximately 115 disk I/Os per second. We recommend that you
size a Model 515 workload using a sizing tool, such as
the IBM Systems Workload Estimator, which you can access at the
following address:
http://www.ibm.com/servers/eserver/iseries/perfmgmt/sizing.html
That said, it depends on what you do with your i5. It certainly runs Java or
a WAS-instance a lot more faster than a model 800 with 800 CPW would do.
But don't expect it to run 5 times as fast with a "traditional" workload.
Some numbers for comparison:
The 515 maxes out at 16 GB memory with 533 MHz, 8x 70 GB 15k SCSI disks
and two RAID controllers, one with 40MB and the other one with a 90 MB
cache.
The 520-M15/25 maxes out at 16 GB memory with 667MHz, 6x 70 GB 15k SAS disks
(well it's not that easy: the load source shall be 70 GB, the other
disks can be up
to 283 GB per diskdrive, but then how to build a RAID5 ...)
The SAS disk are a little faster than the SCSI ones, but you only got 6
arms in
an M15. The M25 is allowed to be expanded beyond this with an EXP24 disk
addition for instance ...
So the question is: how many user-licenses do you need ?
The 515 ends at 40 users, if you exceed this, you need an M25, otherwise it
makes no difference for me.
Regards from Germany,
midrange.com
