Many people are confused about the famous devP (hereafter P Drive or P), used by some applications from Arma 3 Community Tools. In this entry, I will try to demystify what’s P and why it has been implemented.
What is P Drive?
First, P is not a virtual drive but a substitute drive, the concept is very simple: It associates a path (from anywhere in your file system) to a drive letter, in some kind, a shortcut, a letter for a directory. P is well known to be used even necessary to use Bulldozer. To explain a little, most of the tools are prepared with P in mind because it’s simple for everyone, the community and us (BI developers)… But P is not necessary, just a convenience. In consequence, you can setup your work environment like you want, without P, but this would require additional time and knowledge.
Our first thought while preparing Arma 3 Tools was that there is no need of such substitute drive. We actually use it for our work, but it’s not needed. There was a strong push for reintroducing the P: drive from community who was used to it and it’s even easier for us to have some “standard” drive to refer to in Arma 3 Tools.
The first iteration of the tools (without P: drive) was more meant for expert users who should be able to set their own working drive according to their needs in all tools (and may name it even differently than P: drive).
In fine, P Drive is not necessary, but by defining default, it makes the tools easier to setup, use and permit to solve common issues.
Installation
P Drive is now the standard in Arma modding and there is two main ways of using it:
- Can be considered as an
All In Onedisk where you have all data & tools regarding Arma 3 Tools: One place to find everything; - As a sort of representation of ‘what the engine sees’, that’s the reason why settings.ini was introduced.
Firstly, you will need to install Arma 3 Tools, very simple!
- Find in the Steam library (switch the filter to “Tools”) – “Arma 3 Tools”,
- Right click, install (or double click on it),
- The, start “Arma 3 Tools Launcher” (primary tool) once to add (or update) all needed registry entries for the rest of tools,
- You’re ready to go!
If you want to use it as the first case, nothing more simple, you just need to install Arma 3 Tools from Steam (see steps above) and from Arma 3 Tools Launcher, just click on “Mount P Drive” and enjoy your P Drive!
If you want to define your own directory as P, there is only one more step before mounting P, edit your settings. Two ways, run Arma 3 Tools Launcher and press CTRL+E to open the settings dialog or manually, open the file named settings.ini and stored in the root directory of the tools (by default, it’s F:\Program Files (x86)\Steam\SteamApps\common\Arma 3 Tools) with notepad, Poseidon Tools or any other text editor.
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[P_Drive] P_DriveUser=1 P_DrivePath="C:\Users\Tom_48_97\Documents\ArmaWork" |
In the example above, P_DriveUser is set to 1 to tell scripts and tools that real directory used for P is user defined, then P_DrivePath is just the path to your own directory.
 
Once your P is mount and functional, you just need to run DevP to get your P drive ready. It  prepares P with content required for using Arma 3 Buldozer in Addon builder and Terrain Builder if you have Arma 3 installed. Note, if you don’t use Terrain or Object builder, you can skip the devP.
References: “Why is necessary to use virtual drive?” – PettkaÂ
“What is it?” – Tom_48_97Â
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“But P is not necessary, just a convenience.” – is this saying P-Drive altogether is not necessary, or is it saying that using the letter ‘P’ -for- the drive is not necessary?
i would much rather not use subst, as its not more convenient, and just another clutter on my computer. i already have my own directory structure for organization.
You can setup your workstation by configuring every software that require P by default, but you can trust, it’s time consuming and it would be harder to get support because, even with a standardization, each workstation is more or less unique and this is the very reason why it can be hard to debug the tools beside the eventual system issues like I see often.
You show a proper installation but not show how to remove the P: Drive once you don’t need the workstation or the tools any longer..
Worst system ever conceived. Being able to create mods without any use of devP is easy, but to try developing/debugging one using filePatching? Not gonna happen, include directories get infinitely messed up, with the game looking in one place, and build tools looking in another, and thats WITH the fact that each change basically requires a game restart.