Where is my free space??

[Jed Sheckler]

I have a 300gb external drive used to backup my main computer. I use
Acronis True Image to make an image weekly, overwriting the existing image
each time. I also have a variety of other backup data on there. The Image
is about 85gb, and the additional data is another 70gb or so. However my
300 gb drive reports only 40 gb free. My 300gb gross volume nets 279gb
usable space, subtracting the 155gb of actual data (85+70) says I should
have 124gb available. The fact that 124-40=84 leads me to believe that the
image is using (or at least holding) 170gb of space for its 85 gb backup.
Disk cleanup shows no files in the recycle bin. Why is that 85gb not being
freed up when the image file is overwritten?

 

[Ted Zieglar]

"Official Acronis Support Forum"
http://www.wilderssecurity.com/forumdisplay.php?f=64

 

[Dave Patrick]

Has to do with 'slack space'. Consider that every file and directory listing
(no matter what size) takes up at least one cluster. Slack space is the area
between the end of the file and the end of the cluster. It can be calculated
roughly by taking 1/2 of the drive's allocation unit (cluster size) times
the number of files, this is the average wasted space. If you have a lot of
small files then the wasted space figure could be larger.

From a command prompt at the root of the drive in question;
chkdsk
to find out your cluster size (allocation unit)

--
Regards,

Dave Patrick ....Please no email replies - reply in newsgroup.
Microsoft Certified Professional
Microsoft MVP [Windows]
http://www.microsoft.com/protect

:
|I have a 300gb external drive used to backup my main computer. I use
| Acronis True Image to make an image weekly, overwriting the existing image
| each time. I also have a variety of other backup data on there. The
Image
| is about 85gb, and the additional data is another 70gb or so. However my
| 300 gb drive reports only 40 gb free. My 300gb gross volume nets 279gb
| usable space, subtracting the 155gb of actual data (85+70) says I should
| have 124gb available. The fact that 124-40=84 leads me to believe that
the
| image is using (or at least holding) 170gb of space for its 85 gb backup.
| Disk cleanup shows no files in the recycle bin. Why is that 85gb not
being
| freed up when the image file is overwritten?
|
|