During MD Link installation, you will be asked to specify two hard disk locations in which to install MD Link: the first is the application folder and the second is the data folder.
The application folder is where the MD Link program itself is stored. This is customarily under C:\Program Files on Windows, or /usr on Unix. You will not typically need to concern yourself with the files contained within the application folder; the Start Menu entries refer to these, and that is sufficient to run the MD Link constituent programs. The files within the application folder are written once at installation time, and not modified thereafter - until uninstallation, of course. In particular: the application folder will not grow in size after installation.
The data folder is where the files created by MD Link, during the course of performing useful business, are stored. These include solution (.xcs) files, databases, and log files.
A link to the Data Folder is provided under MD Link's Start Menu, for your convenience.
The data folder is customarily under your user's home folder - for example C:\Users\USERNAME on Windows, or /home/USERNAME on Unix). MD Link puts some default files in the data folder at installation time. Thereafter, unlike the application folder, the contents of the data folder will change very much over time as you use MD Link. For example, the solution files you create in the MD Link Studio will be saved to the solutions subfolder by default, and your message histories will be stored under the database subfolder. The latter can require significant disk space, easily into the tens of gigabytes, and so your choice of data folder (and disk) warrants careful consideration. (See Disk Space Guidelines.)
The intent of MD Link's separation of application files and data files in this way is to make for more flexible administration of the program. This is doubly true if you are running MD Link under Windows and the feature known as User Account Control is enabled on your machine - as it will be, by default, on all modern versions of Windows. If this is the case, you will need Administrator privileges in order to install the application files to a protected location such as C:\Program Files, or to install the MD Link server as a service. After installation, the MD Link programs themselves need not run as an Administrator - the administrator privileges are only needed at install time. Furthermore, the data folder need not (and should not) be a protected location which requires administrator privileges.
If you are running under Windows User Account Control and you don't have Administrator access, you should install MD Link to another location, such as your user's home folder. You will be unable to install the MD Link server as a service, however.
This relation is one-to-one, and constant. In particular:
Relocating the data folder for an MD Link installation is not straightforwardly possible. You will need to use a work-around involving reinstallation of MD Link, following these steps:
Now your MD Link installation will have effectively re-set its data folder reference.