32-bit and 64-bit Memory Limitations

[Chuck Lackey]

I know the answer, but need confirmation.

Question:

Is the memory addressable by 32-bit HP-UX 11.00 limited to approximately 3.84GB and therefore adding more memory to a 4GB K580 running 32-bit 11.00 would be stupid?

Thanks,

Chuck

[Ron Irving]

Hi Chuck.

It would seem to me like alot of overkill, wouldn't it? However, for future upgrades, more is always better!!

ron...:)

[Sanjay_6]

Hi,

The 3,75GB limit is for 10.20 i believe. For HP-UX 11.0 32/64 Bit the limit is 4TB.

Thanks
Sanjay

[Chuck Lackey]

Can you or anyone else confirm this?...in writing....URL???....anywhere....???? I can't find it anywhere in HP documentation. All references say "limited to 3.84GB under HP-UX 10.x..." but make no mention of maximums under any flavor of 11.00.

Thanks....

[James R. Ferguson · Accepted solution]

Hi Chuck:

Here's what you seek:

http://docs.hp.com/hpux/onlinedocs/os/11.0/11dev4.pdf

Regards!

...JRF...

[Alan Riggs]

Chuck

You are correct. 32-bit 11.00, like any other 32-bit OS, is incapable of addressing more than 4GB of memory. It is simply not possible to generate more unique memory addresses in 32-bits. Adding more memory will do you no good unless/until you upgrade to a 64-bit installation of the OS.

[James R. Ferguson]

Hi (again) Chuck:

Sorry, the link I posted doesn't resolve to the table summary to which I was pointing. See page-20 "Evolution of Largeness Features in HP-UX" in this link:

http://docs.hp.com/hpux/onlinedocs/os/11.0/11dev4.pdf

The full paper is the "HP-UX 11.x Software Developer's Guide".

Regards!

...JRF...

[Sanjay_6]

Hi Chuck,

you can look into HP Manual, Managing Systems and Workgroups (HP Part No. B2355-90701). Refer to 2nd Chapter : Planning to manage file systems and look under Introduction to Manging file Systems.

here is the link.

http://docs.hp.com/hpux/pdf/B2355-90742.pdf
or
http://docs.hp.com/hpux/onlinedocs/B2355-90742/B2355-90742.html

Hope This helps.

Thanks
Sanjay

[David Lieberman_1]

Chuck,

It is true that HPUX 10.20 can only address 3.85MB of memory. However, adding memory to 4GB on a K580 with 10.20 is useful, particularly on the larger K-class servers (4/5xx).

The memory carriers E0 and E1 both have slots 0a/0b through 7a/7b. By filling all of the slots with 256MB modules, you will maximize the memory interleave of the server hardware and thus reduce memory access latency.

You can check this with the monitor ROM. If I'm not mistaken, a fully populated K580 with 256MB modules will have 32 banks of 32-way interleave - very fast indeed. You won't get this bank quantity or interleave value with any other mixed-module configuration.

HTH
David Lieberman

[Chuck Lackey]

Thanks to all. The table in the doc provided by James gave me the confirmation I needed.

Chuck