User Area > Advice
Computer Hardware and Software Considerations
Processor
- The faster the processor used, the faster you will be able to manipulate and solve your LUSAS models. LUSAS is CPU intensive, especially when solving an analysis. Therefore an increased processor speed will decrease analysis times.
- A dual-core or multi-core CPU will mainly offer improved efficiency when multitasking with LUSAS and other applications simultaneously. If running LUSAS in the background and you are using another application then one core will be dedicated to LUSAS while another will be dedicated to the other application.
- In general we recommend that once a large analysis is set
to be solved, the computer to be left alone so that the CPU can dedicate itself to solving the analysis.
- Modeller currently will run on only one core/processor at a time. LUSAS Solver will use multiple
cores/CPUs during the "Assembling Elements" stage and Fast Solvers will also use multiple
cores/CPUs during the "Solving equations" process. Some of the latest multi-core Intel processors also have the ability to speed up those cores that are in use, when other cores are not being used (called “Turbo Boost Technology”).
- Increasing the processor speed for
multi or single processor
machines would be virtually lost if there is insufficient
physical memory since the analysis would be
"disk-bound" - that is, the processors would be
spending a lot of their time simply waiting to retrieve data
from the system swap file or the application scratch files.
Memory
- The memory requirements for LUSAS when solving medium to
large analyses is typically underestimated when purchasing new
machines in our experience. In general, both Modeller and Solver
will respond significantly better when the processing can be
carried out in physical memory. For this reason, we would
recommend at least 2GB of physical memory. Nowadays it is common to get a machine with
4GB in 32
bit systems and 8GB or more 64 bit systems.
Solvers and disks
- If
you intend to run large jobs it is strongly suggested to use the
LUSAS Fast
Solvers, which can reduce the solving time by a factor of 5 to
10, using multiple processors during the solving of equations.
- Additionally Solver performs significantly better with fast
disks. You should always ensure that there is plenty of disk space free (generally > 12GB or
3x the results file size) when running a large analysis as LUSAS temporary files can become quite large and an analysis can also use up a large amount of Windows swap space. Moving large files off a hard disk temporarily, keeping as much space free as possible and in large contiguous blocks and defragmenting the disk regularly will all speed up the reading and writing of large files like results and output files significantly reducing the time Solver is running for large analyses. Solver will also benefit significantly from a fast
hard drive (and there are various different types available these days) which will speed up reading and writing to disk. If you have two internal local hard drives, then save your model on the one that does not have LUSAS installed on it. If you have three internal drives, have LUSAS installed on one, the model saved on another, and your temporary file locations set on the third. This should help speed things up because reading and writing can occur at the same time on separate disks. Also moving files of the disk you are using temporarily should help to free up space and reduce possible fragmentation of the working files.
Graphics
- From LUSAS version 22.0 onwards,
Direct X is the default option and recommended for most users
on most machines. Direct X is built into all modern versions
of Windows, and as such is not dependent on drivers downloaded
from graphics hardware vendors websites. This means that it is
more suitable for those who do wish to (or not have permission
to) update their drivers. For the same reason, DirectX is
generally more stable over a Windows remote desktop
connection.
- Hardware OpenGL 4.3 is also
supported. In most cases, DirectX and OpenGL 4.3 are
interchangeable, as long as the graphics card drivers are
fully up to date. Users who have issues with DirectX may that
find OpenGL 4.3 offers an acceptable workaround.
Full 64-bit software capability
-
From Version 22.0
onwards, LUSAS provides a fully functional 64-bit Modeller
and Solver, which are used to create and solve new models. Larger models
can be created and solved faster. All
clients are recommended to upgrade and use this version.
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64-bit /32-bit considerations for older
versions
-
For older versions of
LUSAS, a 64-bit Solver can be used with the supplied 32-bit Modeller to allow much larger problems (requiring over 4GB of memory) to be
solved than otherwise possible with an all 32-bit version -
the size being limited only really by the PCs operating system and memory resources. A
64-bit PC with plenty of RAM may solve large problems (between 2.5GB and 4GB) quicker with 64bit Solver than with
32-bit. However, the main gain of using a 64-bit Solver is the size of problem that can be
handled which will be limited by the resources available on
the PC.
-
If versions of LUSAS
prior to version 22.0 are run on a 64-bit operating system
32-bit Modeller will also benefit from being able to use up to the maximum of 4GB of memory (the limit for any
32-bit
application 2^32 bytes) running in 32-bit emulation, allowing larger models to be handled
than possible on a 32-bit operating system. If
you have a 32-bit PC, then you can also set
the data partition in 32- bit Windows to be 3GB rather than the
default 2GB. If you need help in changing the system values to
get 3GB per application in 32- bit Windows please email to support@lusas.com
for more information.
-
In 64- bit Windows the memory limit allocated to each 32-
bit application is 4GB (2^32 bytes) by default
while it could be up to 3GB in 32- bit Windows. Whilst 64-bit Solver results files can be read in the 32-bit
version of LUSAS Modeller for post-processing, we suggest obtaining or upgrading
to a 64- bit Windows machine and installing Version 22 or later
for large jobs. A
64-bit mesh only
Modeller is also available if you are creating a model from an
imported mesh rather than created and meshing geometry.
Hardware requirements
For information on the general type of
hardware specification for use with LUSAS see PC
Hardware Support.
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