Shirt Pocket Discussions  
    Home netTunes launchTunes SuperDuper! Buy Now Support Discussions About Shirt Pocket    

Go Back   Shirt Pocket Discussions > SuperDuper! > General

Reply
 
Thread Tools Rate Thread Display Modes
  #1  
Old 11-27-2009, 02:30 PM
Kalkas Kalkas is offline
Registered User
 
Join Date: Sep 2009
Posts: 19
Question Different sizes of two images of the one and same disk

Hello,

Curiously I compared size of two sparsebundle images of one and the same disk (main mac startup disk) which were located in the same partition, and they had different size. The difference between them was 7 GB; see the attached image which shows two sparsebundle images "current" and "testing." They are images of the same disk having the same content. "Testing" is a later image, made after "current," and there were no changes made on the original disk after "current" was made prior to creation of "testing."

Why is the difference in the size of these two images? Does it indicate that there is some error in the creation of one or both of these disks?

Kind regards,
Aleksandar
Attached Images
File Type: jpg screen.jpg (84.4 KB, 1900 views)
Reply With Quote
  #2  
Old 11-27-2009, 02:32 PM
dnanian's Avatar
dnanian dnanian is offline
Administrator
 
Join Date: Apr 2001
Location: Weston, MA
Posts: 14,923
Send a message via AIM to dnanian
You can't really make judgements based on the external file size of a given image... did you look at the actual size of the volume when you open the image file?
__________________
--Dave Nanian
Reply With Quote
  #3  
Old 11-27-2009, 06:36 PM
Kalkas Kalkas is offline
Registered User
 
Join Date: Sep 2009
Posts: 19
When images are opened, you get disks with different sizes, see attachment.
Attached Images
File Type: jpg disks.jpg (61.3 KB, 1305 views)
Reply With Quote
  #4  
Old 11-27-2009, 06:49 PM
Kalkas Kalkas is offline
Registered User
 
Join Date: Sep 2009
Posts: 19
However, I have compared home directory in each volume, and they appear to be same, with the same size and the same number of items, see attachment.

So, it seems that images are ok. I just wonder why is there difference in sizes of volumes?

Kind regards,
Alex
Attached Images
File Type: jpg home.jpg (48.7 KB, 1290 views)
Reply With Quote
  #5  
Old 11-27-2009, 09:59 PM
dnanian's Avatar
dnanian dnanian is offline
Administrator
 
Join Date: Apr 2001
Location: Weston, MA
Posts: 14,923
Send a message via AIM to dnanian
I don't know. I can only assume that there were significant differences on the source when these were made... but I just can't tell. There had to be *some* difference between these two copies.
__________________
--Dave Nanian
Reply With Quote
  #6  
Old 11-28-2009, 06:10 PM
Kalkas Kalkas is offline
Registered User
 
Join Date: Sep 2009
Posts: 19
The only difference I see with these two images is that "current" was smart updated four times, while "testing" was created once, without any subsequent smart updates. Both images have the same source disk.

Kind regards,
Alex
Reply With Quote
  #7  
Old 11-28-2009, 06:25 PM
dnanian's Avatar
dnanian dnanian is offline
Administrator
 
Join Date: Apr 2001
Location: Weston, MA
Posts: 14,923
Send a message via AIM to dnanian
I'm just not sure why they would be different. I'd have to suggest the source drives were different when they were both last smart updated...
__________________
--Dave Nanian
Reply With Quote
  #8  
Old 11-29-2009, 02:46 PM
Kalkas Kalkas is offline
Registered User
 
Join Date: Sep 2009
Posts: 19
The reason for creating this thread is the peculiarity of the case. It is quite strange that one can get two images with significant different sizes although their last smart updates were from the one same source with the same content.

I have hoped that someone would give some idea why this this is the case.

Kind regards,
Alex
Reply With Quote
  #9  
Old 11-29-2009, 04:42 PM
Kalkas Kalkas is offline
Registered User
 
Join Date: Sep 2009
Posts: 19
New comparisons

I have made new comparisons of the images in question.

The overall size of the images, and their (mounted) volumes are different. However, when comparing the size of all folders at the root (with their number of items), I got equal numbers.

So, it seems that the backup images of the source are practically the same, even though they have significant difference in the overall size. I wonder why is there a difference, when practically all folders of the one volume have the same size with their counterparts of the other volume. There should, therefore, not be any difference in the overall size at all. Is this not quite a peculiar case?

Kind regards,
Aleksandar
Reply With Quote
  #10  
Old 11-29-2009, 06:13 PM
dnanian's Avatar
dnanian dnanian is offline
Administrator
 
Join Date: Apr 2001
Location: Weston, MA
Posts: 14,923
Send a message via AIM to dnanian
It is peculiar, and I really don't know why it would be. I do understand why the images themselves would have different sizes, but not their contents.
__________________
--Dave Nanian
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 10:23 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2024, vBulletin Solutions, Inc.