Lost memory capacity on SSD drive when trying to install update

[robinhill833400]

My C: drive is a 256GB SSD drive. I believed I had more than enough free space to install the 2014 update.
The first attempt to install the update stopped...I think the broadband connection was briefly lost.
I then restarted the download.
During install of my 2014 Building Design Suite, the installer reported it had run out of disk space.
I managed to install Revit and AutoCAD, but did not have enough space for 3DS and other features.
On checking I found I was now left with 15.8GB free, and 2 copies of the Autodesk 2013 Download folder at 48.6GB.
So I deleted one copy, and moved the other to another HDD drive to free up space on the C: drive.
Whilst doing so I realised I had a few other files on the C: drive that could be moved off...a total of 49.3GB.
Having moved the files and emptied the Recycle Bin I was left with only 40.5 GB free on the C: drive.

My maths says: I already had 15.8 GB free
I removed a further 49.3 GB
I should then have 65.1 GB free to continue the update

But I only had 40.5 GB free, so what happened to the other 24.6 GB ?
Whilst trying to delete the extra Autodesk 2013 Download folder Windows reported the file too large to put in the recycle bin and that it was deleting it permanently - I assume it did but wonder if it actually freed the space up?

Anybody got any ideas where the missing memory capacity went and how I can reclaim it?

[Steve_Stafford]

The files that you download, once they are uncompressed are nearly 60 GB. The installer uses the uncompressed files to configure and install the applications. So you have whatever the applications will contribute once installed plus the uncompressed resource files, plus the original compressed files that you downloaded. The numbers I mention are for BDS Premium.

[robinhill833400]

Thanks Steve,
Although that does appear to explain it, I'm not sure it does:
The 15.8GB free memory was after doing the install so was after the files were uncompressed.
I then removed the download folders, with its 2 copies of the install files.
One copy was MOVED to an external drive with no issues
One copy was DELETED...and as it was too large for recycle bin was reported as deleted permanently ie without going into the recycle bin.
So I think the issue may be with Windows 7 and an SSD and deletion of a large file.

By the way, yes this is with BDS Premium.

[Steve_Stafford]

Was the SSD installed and configured as part of your PC purchase or installed as an upgrade later? There are a number of settings and things that are done differently with the them that could account for it if it was installed afterward, assuming the factory can manage to configure it correctly. If you do a search there are a number of sites and articles about SSD optimization but here is one you check out.

[robinhill833400]

It was a later upgrade - cloned from original C: drive. Lots of tinkering ensued with alignment of partitions and other settings.
It's an interesting thought that its to do with the SSD settings...things like TRIM etc could be causing an upset marking blocks not to be used.
Its not been a problem previously with smaller deletions that went through the recycle bin, but this was a big deletion that didnt go via the usual recycle bin route, and I have not had that occur before. I shall explore those possibilities further...

Thanks for the input.