"Mike Hall - MVP" wrote in message
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"Ian D" wrote in message
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"Mike Hall - MVP" wrote in message
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"Ian D" wrote in message
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"Mike Hall - MVP" wrote in message
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"Jgiordano88" wrote in message
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I ran a defragmenting session last night to clear up some space, and
for
some reason my C drive has dropped from 33.1 GB to 29.1

This has happened to me once before, but the other two recent
defragments I've ran cleared up a ton of space. I honestly have no
idea
where the other three GBs have gone and I have not downloaded
anything.
I run a disk cleanup every night.

Thanks for any help.


--
Jgiordano88


Do you ever use the function in Disk Cleanup which deletes all system
restore points except for the last one?

That will get you some space. Defrag will never free up space and, to
date, never has..


--

Mike Hall - MVP Windows Experience
http://msmvps.com/blogs/mikehall/

I wouldn't say Defrag has never freed up space. With the small
allocation units in NTFS, any freed space would be insignificant.
However, with FAT32 and 32KB allocation units, back in the days
of Win9x, Defrag could recover useable space from a badly
fragmented drive. You could possibly recover 1 - 2MB for every
100 file fragments. Maybe insignificant with today's drives, but
a useable amount with the smaller drives back then.



A 1k file will take up 4k of space, assuming that 4k is the cluster
size, regardless of where defragmenter places it..


--

Mike Hall - MVP Windows Experience
http://msmvps.com/blogs/mikehall/

That's my point. If there are a lot file fragments, the unused space
in the last cluster of each fragment will be released during
defragmentation. This won't amount to a whole lot with 4K clusters,
but could with 32K FAT clusters, back in the days of much smaller
drives.



Defragging does NOT release the unused part of a cluster. As far as I
know, two files can't occupy one cluster. regardless of file size.

Small 4k cluster sizes are used by default because more it is more
efficient in terms of space used, unless the hard drive is used to store
great many files of less than 4k size.

The problem with small clusters is that the average size of a file these
days is larger than the 1k of a basic text file. A 36k file will occupy 9
or 10 clusters, all of which can get separated, hence fragmentation. It
gets worse as general file size increases.

Raise the cluster size to 16k, and the 36k file now only occupies 3
clusters. In this way, fragmentation will not be as bad, but if you then
save a great many smaller files, a lot of space will be wasted.

--

Mike Hall - MVP Windows Experience
http://msmvps.com/blogs/mikehall/

My math was off. I was thinking of file fragments using only parts
of clusters, and releasing that space when those partially used
clusters are combined and filled by defragmenting. The fact, of
course, is that the smallest fragment can't be any less than a fully
occupied cluster. If a file is badly fragmented when it's saved,
all clusters would be fully used, and only the last cluster
could have unused space, which would remain the same after
defragmentation.