Size of RAM (rule of thumb only) OpenVMS Itanium vs Alpha

[Lars Funck Jensen_1]

The Integrity servers uses 64 K pages and .EXE files seems larger
than on OpenVMS Alpha.

How much more RAM will I need to configure when moving OpenVMS from Alpha to Integrity ?

[labadie_1]

In last October Sue came with Vms engineering to Paris. I noticed 3 to 4 times more memory on Itanium compared to Alpha. And bench your application. Your mileage may vary, as they say

[Lars Funck Jensen_1]

3 - 4 times is a LOT.
Maybe not for a very smaal Alpha of 256/512MB, but will a need 16 MB
when moving from a 4GB DS20E?

[labadie_1]

You remember when moving from Vax to Alpha ?

We had to have a lot of memory in order to get the best from the Alpha. I have just tested with one model of Itanium.

[Steven Schweda]

> [...] need 16 MB [...]

That was "GB", right?

On the few programs I've built on IA64, the
executables are about twice as large, but the
real question is: How much of your memory is
used by the program(s)? The data should be
about the same size on any system.

How much of the 4GB on your Alpha are you
using now?

Actual testing on an IA64 system is really
the only reliable way to determine this,
especially without more information about the
application than most people normally have.

[Ian Miller. · Accepted solution]

I64 images are a lot bigger than Alpha images for various reasons.

The pagesize according to $GETSYI is 8K on the Integrity systems I have looked at.

hp Integrity servers appear to be configured with lots of memory (min 1Gb). On the small systems I have dealt with then the 1 or 2Gb of RAM they arrived with has been ample.

For your application you will have to try it see.

[John Abbott_2]

Our mileage is yet to begin (awaiting delivery) but we have initially opted for a x3 factor increase (4~12GB). We have some control over memory usage as a portion of what's there today is DB cache.

Last time I looked (for a rx4640) it worked out about £1K per 4GB (4x1GB modules).

Just try to leave yourself room in your configuration, incase you need to add more.

Maybe others might like to post what factor they've opted for & reasons (if any)!

Kind Regards
John.

[Lars Funck Jensen_1]

I think I will ask for 4G as a start for an Integrity 2620.