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Windows 7: Shadow Copies


02 Dec 2009   #1

W7x64 Pro, SuSe 12.1/** W7 x64 Pro, XP MCE
 
 
Shadow Copies

I apologize in advance for the length of the quote below, but it seemed necessary to put a proper focus on my question:

Quote:
The operating systems Windows 7, Windows Vista, Windows XP64, Windows Server 2003 and 2008 offer users the ability to create "Shadow Copies" for protecting their data. This new feature automatically creates copies of files currently in use at regular time intervals. Since Windows only captures changes in the files, not a lot of additional space is normally needed. Accidentally deleted files and folders or previous versions of documents can be easily restored using a convenient command accessible through the context menu. Simply right-click the object you want to restore and click "Restore Previous Versions".

At the moment of installation Windows Vista (or newer) the shadow copy mechanism is set as default. With Windows XP64 and Windows Server 2003/2008 systems it is deactivated by default.

During defragmentation, files on a volume get moved. Vista perceives this as a deletion and creates a new Shadow Copy for the moved file. Because defragmentation requires the moving of multiple files, many Shadow Copies are created, which in turn leads to the higher demand on disk space. This behaviour may overwrite older shadow copies with newer ones. Unfortunately, this can also lead to the deletion of the system recovery points! These consequences are most frequent when using the COMPLETE method.

Shadow copies are filed in the folder “System Volume Information” and cannot be defragmented. This can end up having a negative influence on the result of the defragmentation. There is, on the other hand, almost hardly any loss in performance caused by fragmented shadow copies. Although these files will be displayed as fragmented, they still have only a minimal influence on the operating speed of your system.

You could disable the shadow copies to achieve improved defragmentation results but you would then wind up losing the operating system’s built-in backup functionality. That’s why we recommend your leaving the shadow copies enabled.

Microsoft is already aware of this problem, as this issue also occurs in the Windows native defragmentation software. More details may be found in this article from Microsoft: Shadow copies may be lost when you defragment a volume

In Windows XP64 and Windows 2003 Server, this problem will not occur as long as storage volumes have been formatted with a cluster size of 16KB or larger. If this cannot be changed or Windows Vista is in use, this issue can be avoided by first performing a STEALTH defragmentation followed by a SPACE defragmentation.
If I comprehend what was said, the shadow copies are necessary for the proper functioning of the backup system and System Restore points, but while I do care about the restore points, I don't care about the Windows 7's backup system, because I use third party software for that purpose.

For this reason, I guess I have to leave the shadow copy function enabled, but looking in my file manager, there are ~28 items listed and looking at O&O's graphical analysis, they are taking up a fair number of GBs of the partitions space.

Since these locked files have a tendency to increase fragmentation of other files on the partition, I've been trying to figure if there is a good and safe way to determine which, if any of these shadow copies can be deleted? Those 28 copies were created on only 4 days, so I'm guessing that each partion got it's own shadow made, or they are only incremental portions of a whole.

How would one predetermine the effect of deleting any particular shadow copy?


My System SpecsSystem Spec
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02 Dec 2009   #2

Windows 8.1 Pro (x64)
 
 

Quote   Quote: Originally Posted by seekermeister View Post
Since these locked files have a tendency to increase fragmentation of other files on the partition...
Don't have an answer for your question really. But no Shadow Copies don't actually case fragmentation until the HDD is almost filled. Windows actually places the Shadow Copies at the far right end of the HDD away from the main data.

What the quote you referenced is about how defragmentation has a negative effect with Shadow Copies (SC). When the defrag moves a file on the HDD, SC sees that as a deletion and copy operation causing SC to create a copy.
My System SpecsSystem Spec
02 Dec 2009   #3

W7x64 Pro, SuSe 12.1/** W7 x64 Pro, XP MCE
 
 

Quote   Quote: Originally Posted by logicearth View Post

Don't have an answer for your question really. But no Shadow Copies don't actually case fragmentation until the HDD is almost filled. Windows actually places the Shadow Copies at the far right end of the HDD away from the main data.
Not altogether, in the attachment, almost all of the gray blocks are System Volume Information, which is composed mostly of shadow copies (plus many of the other color blocks contain system volume information files also).
Quote:

What the quote you referenced is about how defragmentation has a negative effect with Shadow Copies (SC). When the defrag moves a file on the HDD, SC sees that as a deletion and copy operation causing SC to create a copy.
Yes, but it seems that it goes both ways...defrag effect copies...multiple copies scattered across the partition effect fragmentation.

Those blue block at the very bottom of the graph are from a game that I installed recently, and I'm pretty sure that doesn't include all of the game's files.


Attached Thumbnails
Shadow Copies-o-o-defrag.png  
My System SpecsSystem Spec
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02 Dec 2009   #4
whs
Microsoft MVP

Vista, Windows7, Mint Mate, Zorin, Windows 8
 
 

Shadowcopies cannot be deleted individually. Depending on the size of your OS partition, shadowstorage will use 5, 10 or 15% of your partition space. A shadow is written every time you install or uninstall something (even updates) and one is written per day. If you had 28 shadows in 4 days, you must have been installing a lot. If you want to look at the size of your shadowstorage, go into elevated cmd and type vssadmin list shadowstorage and hit Enter. That will give you 3 numbers - used, which is relatively irrelevant, allocated, which is the amount VSS has currently grabbed and maximum, which is what it will ultimately grab. If you want to look at individual shadows (restore points), type vssadmin list shadows and hit Enter. If you want to resize the shadowstorage, type vssadmin Resize ShadowStorage /For=C: /On=C: /MaxSize=300MB - note, the minimum size is 300MB but you can choose any amount larger than 300MB - e.g. 5GB. Also note the blanks in front of the slashes.
My System SpecsSystem Spec
02 Dec 2009   #5

W7x64 Pro, SuSe 12.1/** W7 x64 Pro, XP MCE
 
 

It seems that mine is set a bit larger (20%-20GBs). The used and allocated are 19.+GBs each. If I were to resize this, what would happen to the copies already made, would they be deleted? I'm not necessarily against that, because that is the purpose of this thread, but I really like to know what to expect. Is there some ratio to expect as far as the number of restore points would be possible with any given size? I want System Restore to be able to go back more than a day or two.
My System SpecsSystem Spec
02 Dec 2009   #6
whs
Microsoft MVP

Vista, Windows7, Mint Mate, Zorin, Windows 8
 
 

When you resize, all shadows will be deleted. But that should not be a problem because you will quickly get new ones. Each shadow is about 1GB +/- in size. So that gives you an idea how many you get with the shadowstorage you plan to allocate.
One thing you should know is that the Volume Shadow Copy function (VSS) of Vista is not very reliable. Very often you will be unable to reset to a prior restore point - it just does not always work. But they are handy in case you accidently deleted files that you did not want to delete. With Shadow Explorer ( ShadowExplorer.com - About ) you can then reimport those lost files from prior shadows.
For the emergency system restore I suggest imaging. I use different imaging programs for my different systems, but Macrium ( Image your system with free Macrium - Vista Forums ) is by far the easiest, fastest and most reliable.

PS: I am puzzled that you think your shadowstorage takes 20% - it should not be more than 15%. How big is your OS disk?
My System SpecsSystem Spec
02 Dec 2009   #7

W7x64 Pro, SuSe 12.1/** W7 x64 Pro, XP MCE
 
 

whs,

Quote:
PS: I am puzzled that you think your shadowstorage takes 20% - it should not be more than 15%. How big is your OS disk?
The partition that Windows 7 is on is 100GB, and the Command Prompt commands that you gave me said that the maximum size is 20GB...and and the used and allocated were over 19GBs. That works out to 20% of the partition size as maximum.

As far as Imaging, I'm using Paragon 2010 and TI 2010. They are more than adequate for their jobs.

EDIT: Going off in a bit of a tangent, when I first started using TI a few years ago, I asked on their forum whether the partititon containing the .tib files should be defragged or not? The responses that I got were not to, but I got the feeling that those who replied were speaking from their gut, rather than actual knowledge.

I haven't gotten around to using TI yet, but I have Paragon, and just as before, the image file that it produced it solid red (fragmented). Until told otherwise, I'll leave it that way, but I would like to hear what you have to say about it?
My System SpecsSystem Spec
02 Dec 2009   #8
whs
Microsoft MVP

Vista, Windows7, Mint Mate, Zorin, Windows 8
 
 

1. I guess you are right. It is using 20% - but it should not. But you can always resize it. My Windows 7 partition is 75GB and the shadowstorage is 5%.
2. Paragon is a good product - very fast but also not so easy to use. But if that does the job for you, what more can one ask for.
3. I have no clue regarding the fragmentation. I would check with WinDirStat ( WinDirStat - Windows Directory Statistics ) It gives you a little better picture than O&O.
My System SpecsSystem Spec
02 Dec 2009   #9

W7x64 Pro, SuSe 12.1/** W7 x64 Pro, XP MCE
 
 

I decided to reduce the size to 10GB, since that seemed like a reasonable compromise, but it didn't have the effect that I hoped for. Instead of eliminating the scattered portions of the System Volume Information, it got rid of the more consolidated portion at the end of the drive, as can be seen in the attachment below. Looking in the file manager, there is now only 3 files, rather than 28, which is good, but I don't understand why there are even 3?


Attached Thumbnails
Shadow Copies-o-o-defrag-2.png  
My System SpecsSystem Spec
02 Dec 2009   #10
whs
Microsoft MVP

Vista, Windows7, Mint Mate, Zorin, Windows 8
 
 

I think you worry too much. If anything, the impact will be so minute that you will never know it. If you like performance, use an SSD. Have a look at the transfer rate and access time of mine - and everything is instant. Fragmentation is no SSD problem - you never defrag. Check your HDD with HD Tune ( http://www.snapfiles.com/get/hdtune.html ).

My System SpecsSystem Spec
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