SUMMARY: Datasize limit on E450 running Solairs 2.5.1

From: Karl Baker (
Date: Thu Aug 20 1998 - 14:24:17 CDT

Thanks to all that responded. The original question is attached below.

I have received several emails from people confirming my suspicion that
approximately 4 GB is the limit for any process address space on a 32 bit
OS. Solaris 2.5.1 as well as Solaris 2.6 are not fully 64 bit OS's.
Apparently, Solaris 2.7 will be a 64 bit OS and won't have this problem.

Thanks to Ray Trzaska, Adam S. Moskowitz, William Hathaway, and the several
others who confirmed the above.

Casper Dic informed me that a process can use at most 3.75 GB, consistent
with my findings. He also asked what shell the user was using: c-shell.

Chris Marble also pointed out the obvious fact that even if my OS did
support > 4GB process address spaces, the performance would be adversely
impacted due to swapping. However, at least the job would run...

Thanks again for all the input,


--------------------- Original Question ---------------------

Hello fellow Sun Admins,
I have a user that needs to run jobs larger than 3.9 GB on an Enterprise
450 configured with 4GB RAM and approximately 8.5 GB Swap space. The system
is running Solaris 2.5.1 HW4/97, fully patched, including kernel patch
103640-20 (we have not had an opportunity to install the latest revision).
The user has set the following limits:
% limit
cputime unlimited
filesize unlimited
datasize 3932152 kbytes <--------------
stacksize 8192 kbytes
coredumpsize 0 kbytes
descriptors 1024
memorysize unlimited

We have tried setting the datasize limit to 6291444, but when we display
the settings, we see:
datasize 2097140 kbytes
We have also tried unlimit datasize, but again we only see:
datasize 2097140 kbytes

It would appear that datasize resets after 4GB...

Q. Is it possible to configure this system to run jobs that require more
than 3.9 GB of memory?

Thank you in advance, and I will, of course summarize.

Karl Baker x.2360
Unix Systems Administrator, Postmaster
MIS Department

Matrox Electronic Systems Inc.
1055 St-Régis Tel: (514) 822-6000
Dorval, Québec Fax: (514) 822-6262
Canada, H9P 2T4

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