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64 bit

64 bit

64 bit


We all know that 32bit OS does have a limitation for each Process. And CATIA  process (CNEXT) will crash with windows 32bit when it will reach ~1.5Gb or ~2.5G if the /3G is defined.

I would like some feedback from 64bit users.

Is your CNEXT64 (?) process crashing when you reach some memory limit?

Can your CATIA process go above your actual RAM ? Like you have 8G RAM and your process goes 24G (using swap) ?

PLZ provide info about 64 OS (vista or XP) and CATIA level (R18/19..V6) when you give facts.

Thank you everyone.

Eric N.
indocti discant et ament meminisse periti

RE: 64 bit

Eric - I can't dole out much techno jargon when speaking about 64 bit computing, but what I CAN say, is that I've not ever had a single memory limitation warning or termination on 64 bit Catia, (any version from R16 to current) running on AMD Opteron (dual 250) with 8 GB RAM per processor, on Windows X64.  It has never been an issue at all.  In fact, I automatically upped the RAM when I built the machines, just because it was no longer a limitation...

My work has never involved simulation, but I do plenty of DMU, and file translations that would normally crash any 32 bit system.  Sometimes, the 64-bit  Catia is the only way that I can translate certain files - especially those over 200 MB, or those that have been translated 2 or 3 times already through other CAD packages.

As far as swap goes, I've never seen 64-bit Catia even come close to utilizing the available RAM that I have, so I'm not sure what would happen.  Do you have a good way to test it?


Catia Design|Catia Design News|Catia V5 blog

RE: 64 bit

I have been running V5R18 on a 64-bit, 8GB RAM machine for a few months. No crashes that I can remember. I have switched over to our 32-bit machine occasionally and it still does crash. As for RAM usage, I have never seen it go above 3.5GB.


RE: 64 bit

No problems so far with 64bit catia r18, have had it up to 5gigs on the cnext process without problems but as mentioned here it is more stable, faster, startup, no crashes and scripts that were unstable on 32bit now works like a charm.

RE: 64 bit

I have used V5R16SP9 a bit, V5R17SP7(?) a bit, but mostly V5R18SP6 on 64-bit Windows (XP-Pro) for about a year now. Overall it is significantly more stable than 32-bit, though I don't know how much to attribute to improvements in video drivers etc.

Occasionally I have worked with large assemblies of aircraft data, that has used up all 8GB of ram and pushed into about 15GB of hard disk space. Catia has been fine with this, just becomes amazingly slow on account of slow hard disk performance. In the process of loading this sort of thing, Windows has thrown up errors that it is increasing virtual memory, but Catia keeps on chugging away anyway.

My workstation uses dual quad-core Xeon procs, but Catia is still a single cpu sort of program so having 8 cpu's doesn't help. I have actually convinced our IT department to buy faster single-quad pcs, rather than slower dual-quad for the same price.

One major hangup I have come across has been in capturing video of simulations (using Delmia V5). Since it is a 64-bit process, the built in video capture wants a 64-bit video codec, which has proven to be both rare and problematic.

I also know you can install and run 32-bit Catia on 64-bit Windows. According to Dassault's documentation this allows the CNEXT process to use up to 4GB of ram.



RE: 64 bit

Some feedback about running on UNIX (AIX), please? Same CATIA 64-bit, of course.


RE: 64 bit

Thanks Mark,

From your feedback I can see that the memory allocated to the process is not limited by the RAM and windows will provide more 'memory' with virtual memory on drive.

Thanks you very much for this info.

Anyone else can confirm this?

Eric N.
indocti discant et ament meminisse periti

RE: 64 bit

I once had to run CATDUAv5 on a big assembly (wouldn't open on 32-bit at all), trying to clean some errors. It raised the Task manager "meter" up to 10.5G+, it took several hours, but it didn't crash. Now this was a while ago (more than one year), I ran this in R16, SP8 I believe...  

Best regards,

RE: 64 bit

do you remember how much physical memory you had in your computer?

I am looking for a confirmation that the memory process can go far above physical memory.

Eric N.
indocti discant et ament meminisse periti

RE: 64 bit

People often get confused about memory, physical, virtual, Address space etc.

The difference between 32bit and 64bit is address space and this has nothing to do with physical or virtual memory. Address space is the total number of memory address available (consider them as pigeon holes to put stuff). The maximum available address space is given by 2^32 and 2^64 which give total address spaces of 4gb for 32bit and 16tb for 64bit respectively.

In windows operating systems the address space is split 50/50 between private address space (dedicated to an application) and shared / kernel address space (dedicated to the OS and the shared portions of applications). This is where the 2gb limit for 32bit CATIA on 32bit os comes from (4gb / 2 = 2gb). The other thing it is important to note here is that every application that starts is allocated 2gb of private address space, so if you start 3 applications windows has told all 3 that they have 2gb of addresses giving a total of 6gb. which is obviously greater than 4gb this can occur because all the applications are given the same 2gb range of addresses and it is the memory manager that is responsible handling this. Whilst you cannot change the total available address space (it's an absolute limitation of the maths) on windows XP you can change how it is split between private application space and shared kernel space, this is done by adding the /3gb switch into the boot.ini file. This shifts the boundary to 3gb private address space and 1gb shared kernel address space. Because CATIA primarily requires private address space this is a useful thing to do. However, MS do say you use the 3gb switch at your own risk, the reason for this is if you have an application that is not large address space aware it can end up trying to store data in a location it cannot read or write to and this will cause an unhandled exception in the best case or a blue screen in the worst case.

The private process address space limits for the various combinations of CATIA and Windows are as follows:-
Win32 + 32Bit CATIA = 2gb
Win32/3gb + 32Bit CATIA = 3gb
Win64 + 32Bit CATIA = 4gb (may require os patch)
Win64 + 64Bit CATIA = 8tb

Address spaces are the absolute limits of available memory, if an application tries to exceed the available limit it will crash (unhandled exception or click ok to terminate (handled exception)). Where the address relates to (physical or virtual memory) is up to the operating system. The operating system will move the data between physical ram and the page file dependent on the access requirements of the data. This means that you can run a CATIA session that uses 10gb of process memory on a machine that only has 1gb of physical ram, but it will require ~11gb of pagefile (virtual memory) as well. It will also be exceptionally slow as disk access is one or two orders of magnitude slower than memory access. Even the largest workstations can only hold 64gb of physical memory and this is a long way short of the address space limit of 8tb for 64bit windows, so the page file is here to stay for the forseeable future (particulary if you look at the cost of such a machine). Also bear in mind that a some point you want to turn the computer off and assuming that all the data held im memory is important it will need writing to some sort of storage medium which even with fast disks 10gb of data take a while to write.


RE: 64 bit


The machine I was using (and I still do, once in a while) is an IBM Intellistation Z Pro, 2x Xeon @ 2.66GHz and 8G of RAM. Win-XP-64, SP2.

PeterGuy, nice "tutorial"... Thanks...  

Best regards,

RE: 64 bit

Indeed, nice explanation, a star from me.


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