Subject: Speeding up WEAP calculations with a RAM disk Posted: 12/6/2007 Viewed: 71493 times
Speeding up WEAP calculations with a RAM disk Jack Sieber jsieber <a href="mailto:jack.sieber@sei-us.org">jack.sieber@sei-us.org</a>In response to various users' questions, here are some tips on using a RAM disk to speed up WEAP calculations.
Best regards,
Jack
Using a RAM Disk with WEAP
In some cases, especially with larger datasets, the performance of WEAP can be greatly improved by using a RAM disk to hold the working copy of a WEAP area.
First some background on WEAP's internal workings... When you open an area, WEAP makes a copy of the area folder. By default the data files are placed in the _WORK folder (below the WEAP Areas directory), however you can instead have WEAP make use of a RAM disk to hold this data. A RAM disk uses an area of your PC's memory to simulate a physical disk drive. Because the RAM disk uses RAM (random access memory) rather than a mechanical hard drive, it will typically be many times faster in terms of reading and writing data files.
If you are considering using a RAM disk, there are a number of issues to consider:
* You will need to have administrator rights on the PC since you will need to set-up a RAM disk.
* RAM disks are not part of a standard Windows installation. Thus, you will need to find some software that can setup a RAM disk on your PC. A number of alternatives are readily available on the Internet. One tool we have used successfully in the past is DataRam RAMDisk ( http://memory.dataram.com/products-and-services/software/ramdisk ), which is free for RAMDisks up to 4 GB--plenty for WEAP. (Some other users have reported success with http://members.fortunecity.com/ramdisk/RAMDisk/ramdiskent.htm ). The instructions for installing the RAM disk will vary depending on the RAM disk you use.
* You will need to setup the RAM disk with adequate amount of space to hold all of the data and result files in the largest WEAP area you are working on. Check the total size of each of your area folders after having calculated and saved an area. Bear in mind that the majority of storage for an area is taken up by results files (result*.*). We suggest you create a RAM disk 1.5 or 2 times the size of the largest dataset you want to work on, but you should always leave a fairly large amount of free space to allow for an area's size to grow over time.
* Bear in mind that any memory you devote to a RAM disk will be memory that is no longer available for running other programs. We only recommend using a RAM disk if (a) your PC has at least 1.0 GB of RAM and (b) the PC is devoted to running WEAP (or at least WEAP is one of the main pieces of software you use on the PC). You can turn the RAM disk off when you are not using WEAP.
* Some people have asked whether using a RAM disk makes it more likely that data will be lost should a PC crash (e.g. if electrical power should fail). In general, this is not an issue because, even though in using a RAM disk your working data files now reside in memory, whenever you save data the information will automatically be copied back to the hard drive folder containing your area.
* Once the RAM disk is setup you will need to tell WEAP to use it instead of the "_work" directory that it uses by default. When WEAP is not running, edit the text file weap.ini in the WEAP Areas directory (in WEAP, go to Help, About to see where the Areas directory is), adding the following line anywhere after the line [General]
WorkDir=R:\Temp
Replace "R:" with the drive letter of the RAM disk. The Temp directory will be created if it doesn't exist. If the drive doesn't exist, or it can't create the directory, it will use _Work instead (and tell you so). You can check the current working directory WEAP is using from the Help: About screen in WEAP. To later disable the use of the RAM disk by WEAP, simply delete this line from weap.ini (when WEAP is not running).
Mr. Jack Sieber
Subject: Re: Speeding up WEAP calculations with a RAM disk Posted: 10/1/2010 Viewed: 68924 times
The Cenatek company was bought by Dataram, and they are once again offering a free RAMDisk: http://memory.dataram.com/products-and-services/software/ramdisk It works on Windows XP, Vista and Windows 7, and creates a RAMDisk up to 4 GB, which should be plenty for WEAP.
Jack
Mr. Jack Sieber
Subject: Re: Speeding up WEAP calculations with a RAM disk Posted: 8/22/2012 Viewed: 63274 times
Several benchmarks conclude that the QSoft RAMDisk is faster than other RAMDisks. Diclaimer: I have not done a comparison with different RAMDisks and WEAP--I am only reporting what I have read from searching the web.
