Helping people with computers... one answer at a time.

When you install software on a drive other than C: you may be surprised to see space disappear from it anyway. I'll look at some reasons why.

I am using the trial version of Windows 7 Enterprise 64 bits. I installed the operating system on a 50GB partition, and all other applications on a separate 50GB partition, the remaining space of my 320GB hard drive is for data (word documents, audio and video files, etc). Initially, after installation, windows 7 uses around 20 GB of the partition. But after installing all the applications softwares (Microsoft Office 2010 trial, Adobe CS4, etc) the space available on drive C is only about 15 GB. Can you please explain to me why and how to avoid this situation.

I'm not terribly surprised.

One probable reason is that the system drive (typically the C: drive) is special.

However, there are a couple of other things that could be going on as well.

I'll review a few possible causes, and which of those you can control.

Installing on D: Often Installs on C: Also

I'll use "C:" as the system drive and "D:" as the "other" drive as my examples throughout - your system might be different, but the concepts will still apply.

Many applications install some of their core components to C: even though they'll install the majority of their software on D:. This seems counter intuitive, particularly since it a) asked you where to install, and b) you told it D:.

"One approach is to do just a little detective work as you install software"

The problem is that many of these applications may install shared or common components used by other applications as well - and one way for those applications to know where these common components are is by installing them in a standard place.

And that standard, "special" place is on C:.

Installing The Program on D: Might Place Data on C:

Many applications install both programs and data, and the data may not be installed in the same location as the program.

For example, it's possible that a product might install a default set of templates or example documents into your "My Documents" folder, or somewhere else associated with your login account.

I'll bet your "My Documents" folder is on your C: drive.

You can move "My Documents" to another drive, if you like. I have these instructions for moving My Documents in Windows XP, and I believe the process is the same for Vista and 7.

Installing The Program on D: Might Still Place More Data on C:

Check to see if you have a folder "MSOcache" in the root of C:.

MSOcache is a copy of your Office Installation files that the Office Setup program may place on your machine in an effort to make it easier should you ever need those installation media again later. For example some features can be marked as "install on first use"; MSOcache avoids your needing to grab the installation media to perform that installation.

MSOcache can appear on other drives, but there's no reason it couldn't show up on C: as well. In fact that's exactly where I found my own copy of MSOCache.

Temporary Files

Many setup programs create and use temporary files, and then like a five year old boy they are sometimes less than fastidious about cleaning up after themselves.

Since temporary files are typically placed in the temporary folder, and that folder typically resides on C: the result is that additional space gets used up on C: when you might not expect it.

The temporary files folder is identified by an environment variable called TEMP and is typically safe to empty. The disk cleanup utility may also clean its contents.

You can also move the temp folder to another location; see the related articles for instructions.

Detective Work

Of course it could be something entirely different. Smile

One approach is to do just a little detective work as you install software. Using a tool like TreeSize Free you could take a before and after look at where disk space is being used and what's changed.

TreeSize is actually just a good tool in general to understand exactly what's taking up large amounts of space on your machine.

Article C4710 - January 15, 2011 « »

Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

Allen Jenkins
January 18, 2011 8:37 AM

I've heard that Dell computers use drive D:\ as the default for Program Files, etc.

I have HP, that defaults to C:\, and a train simulator that defaults to my drive C:\Program Files(as most installations do)...but it must access the Internet, so to bypass the Windows Protective Services, I install it to C:\TS2009, and allow the .exe files to access the Internet through my firewall & Internet Security software.
This has eliminated a ton of problems experienced by other users of this game.
But I can't figure why people want to change locations for TEMP, etc, because if trouble happens, the files are spread out all over the place & seems that would be harder to diag.

Peter B
January 18, 2011 1:54 PM

I take the view that anything that relates to the 'operating system' (including links with the registry, shared / common components, etc# goes on the OS (C:) drive, as it all needs to be backed up (and restored) together. I have a separate (logical) drive for my data files. I do keep portable applications (= nothing needed but the contents of the program folder; no install required) away from the C drive. As you can see on some of Leo's other answers on copying your software to another PC, you can do nothing with the majority of the contents of the program files folder - it won't work without the matching registry entries, etc. So treat it all as a single entity, and hold it all on a single drive.

Rich Aubin
January 18, 2011 2:24 PM

I have been "optimizing" computer systems for many years. I've always run my system with a C: boot drive and a physically different D: data drive. Most programs can be installed to run from D: But only a few will require to be installed from/to the C: boot drive. I've run my HTPC for 6 years straight 24/7 only needing to shut it down for hardware upgrades and to replaced a couple failed components.

Along with the aforementioned tips by others, there are some more things you can do to keep your C: drive clean.

You can move your swap file over to the D: drive.
Set up a normal procedure for "cleaning" the junk files. Just be careful what you delete. There are utilities such as "CCleaner", and "Advanced System Care" that are for the most part conservative in their settings.

The BIGGEST drive space usage comes about if you are apt to install and remove a lot of applications. Most of the time, each new install will create a "restore point". And guess what? Unless you actually purge those restore points you will have dozens (or more) copies .. each one using many GB of drive space. For my system, I use a Vertex 30 GB SSD. My C: drive is never less than half full. (about 12 to 15 GB used out of 30). My D: drive is a fast SATA 120 GB.

I'm running a Win 7 Pro 64-bit OS with a 4-core 2gb processor that runs 45 wts.

Use Advanced System Car to clean your registry and get rid of junk files. That and CCleaner are freeware apps. For a few bucks more you can register the "pro" version of Adv. Sys. Care that will give you some more options. But the freeware aps will usually be all you need.

When you uninstall a program, after doing a system scan for junk files, also use the Registry Clean option available in CCleaner or ASC.

Next right click on your C: boot drive and bring up it's "properties". Click on the "Disk Cleanup" button. On the next window that pops up, click on "More Options". In the "System Restore and Shadow Copies" box, click on the "Clean up" button. Read the info there. That will delete all BUT the most recent restore point. In most cases that can get you back several GB of space.

Just be sure everything is working okay and you have current backups. The only downside to deleting all but the last restore point is that you won't be able to restore back 2 or more copies. I've never had to use any more than the most recent. But then I frequently do full and incremental backups. Of course YMMV as they say.

One benefit I've always experienced by using a minimal boot drive space is that it allows me to take advantage of the BIG performance increase by using a fast SSD. And keeping that drive small allows you to take of the falling prices for the smaller SSDs.

January 18, 2011 4:42 PM

I noticed my C:/ drive filling up rapidly also. I hadn't installed any software, so I was puzzled, until I was in Windows Media center and noticed that I had accidentally turned on the video recorder for a scheduled recording every week. It is very easy to do, especially by novices like me. I was only trying to learn to use Win 7 Media Center and just clicked the wrong buttons.

January 18, 2011 5:39 PM

You forgot the best tool from Microsoft, for free, at:
Choosing either Protection, Clean up or Tune up. Clean up will clean the registry and delete all temporary files. Protection will clean the attached hard drives from all known MALWARE at that time. Tune up is a defragmenter program.

January 19, 2011 4:14 AM

In addition to Rick's message : In noticed that the winsxs folder (vista/7) can grow out of proportion (10 gb in my case!); this is where shared and/or old dll's are stored. Better left alone; discspace is cheap.

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