topic Re: Max Memory... in Operating System - HP-UX

Max Memory...

Sejal Joshi — Thu, 25 Oct 2001 13:34:02 GMT

Can I install 8GB memory on N-class server running HP-UX 11.x 32bit OS??
Is max memory on N-class for 32bit OS & 64 bit OS is same??

Thanks,
Sejal

Re: Max Memory...

Craig Rants — Thu, 25 Oct 2001 13:40:21 GMT

Yes, 8GB will work. We have that much running on our N.

Good Luck

Re: Max Memory...

linuxfan — Thu, 25 Oct 2001 13:46:18 GMT

Hi Sejal,

The N-class (now known as rp7400) has a maximum capacity of 32GB of memory so you should be able to use 8GB.

http://www.hp.com/products1/unixservers/midrange/nclass/specifications/index.html

-Regards
Ramesh

Re: Max Memory...

Ajay Sishodia — Thu, 25 Oct 2001 13:49:02 GMT

Sejal

you can have 8Gb on N class, that will work. Although I don't think you can have 32bit OS on the N-CLASS. It should be 64bit and the max is 32gb memory on a N class

Re: Max Memory...

Sejal Joshi — Thu, 25 Oct 2001 13:49:55 GMT

I am running 32bit OS on N-class...I am reading different docs. that says 32bit OS can address upto 3.75GB of ram...Is that not true for N-class??

Re: Max Memory...

G. Vrijhoeven — Thu, 25 Oct 2001 13:57:57 GMT

You should be able to put in max 32 GB mem in a N4000 . 32 bits os can adress 2^32 bits mem

Re: Max Memory...

Alan Riggs — Thu, 25 Oct 2001 14:07:49 GMT

A 32-bit OS can address only 4GB of RAM. 64-bit HP-UX 11.~ can create multiple 4 GB "memory windows" for 32 -bit applications.

The N-class can certainly take 8GB of RAM. I am among those who thought that it was not possible to run 32-bit 1.00 on an N-class server, though. Please run

file /stand/vmunix

and check the results.

Re: Max Memory...

Roger Baptiste — Thu, 25 Oct 2001 14:16:56 GMT

Sejal,

N-Class can certainly
accomodate 8Gb memory.
Your question was whether
your 32-bit O/S can address
it?

32 bit can address
-> 2^^32 = 4Gb Memory.

But, using memory windows
feature, your applications
can access memory beyond
the 4Gb limit for specific
purpose (shared memory).
Please check the document
/usr/share/doc/mem_mgt.txt
and mem_wnds.txt.

I have never used this
feature, but it is there.

-R

Re: Max Memory...

linuxfan — Thu, 25 Oct 2001 14:34:31 GMT

Hi sejal,

N-class only supports 64 bit 11.0.

But yes if you are running 32-bit 11.0 on a different hardware, then the max you can use is 4GB.

A5414867 talks about memory limitations for older OS'es(10.x etc)

To utilize the maximum shared memory (on 32 bit ) you will have to compile your programs using SHMEM_MAGIC.

-HTH
Ramesh

Re: Max Memory...

Dave Wherry — Thu, 25 Oct 2001 16:07:50 GMT

As the others have mentioned, yes you can put 8GB in an N class system.
Something else to think about is the density of the memory you put in. An N server can have 1 to 4 memory carrier boards. Each board has 8 slots. Each time you add memory you use 2 slots. Memory comes in 512MB, 1GB and 2GB DIMMs.
Your minimum is 1 carrier with 512MB which uses 2 slots. This leaves you with 6 slots available. Your maximum is 4 carriers with 32GB. When you buy 2GB DIMMs you get two 1GB DIMMs. You have to buy the 2GB increments to go to the max.
Think about how much memory you may ever want to put in this system. It costs more to use 2GB DIMMs but you have the most headroom for growth. If you do not think you will grow beyond 8GB, two carriers with 512MB DIMMs is the cheapest way to go. You need to find a combination that meets your current needs and budget and may allow for growth.

Re: Max Memory...

Bill Hassell — Thu, 25 Oct 2001 16:24:56 GMT

Looks like a clarification is needed: The N-class cannot run a 32 bit version of HP-UX...it will only run in 64-bit mode which means you can install 8 Gb or even 32 Gb of RAM. The operating system will address all of it.

HOWEVER, there are two types of programs that can run on HP-UX 64bit: 32bit and 64bit. Any 64bit application has essentially unlimited access to RAM, but 32bit application do not...they must run in an address space limited to 3.75Gb, and to further restrict 32bit applications, they cannot use a dataspace more than 940 megs (or up to 1750 megs with special conditions and compile ooptions.

So if you have 8Gb of RAM but are running programs that are only 32bit capable programs, then only 3.75Gb of RAM is available for those programs, just like 10.20 and earlier. Without recompiling (and perhaps some recoding) into 64bits, a 32bit appication cannot address any additional memory.

Now there is a feature in HP-UX called memory windows that allows the running of independent programs in separate 3.75Gb windows. This works as long as the applications do NOT share any memory with each other. You can read about memory windows at docs.hp.com

Re: Max Memory...

Sejal Joshi — Thu, 25 Oct 2001 17:33:23 GMT

Thanks Bill for information...
I am having one more question...
We have a application name MDE...

Each of the MDE aplication processes
(32bit) uses 300MB of ram. Under a 64
bit os, wouldn't that mean that each
process can get 300MB out of that 8 gb
pool? IE although each process is
limited to 3.75GB, we can still
utilize the extra memory since each
process doesn't need more then 3.75GB
of space?

Can you please give me more info on that??
Can 32 bit process go beyond 3.75
GB?? As we have 64bit OS....all 8gb memory is usuable or 3.75 gb for 32 bit apps....What happened if all 3.75gb memory is in use?? Is 3.75GB limitation is per 32 bit process or across all 32 bit processes that running on the system??

Thanks,
Sejal