VISSAADMIN Resize Shadow Storage

Question

_{Tuesday, November 28, 2017 9:03 AM}

during safety copy I get the message: "VISSAADMIN Resize Shadow Storage". how do I determine which parameter to adjust?

And how do I ad it?

:) Søren

:) Søren

All replies (5)

_{Wednesday, November 29, 2017 1:53 AM ✅Answered | 4 votes}

Hi,

Which drive do you want to resize?

If it's system drive, you have two methods to resize it.

Method 1: Resize it via UI.

1. Right click This PC, select its Properties.

2. Click System protection at the left pane.

3. Jump to System Protection tab, click Configure... button.

4. Scroll the Max Usage slide to adjust the size to what you desire.

5. Remember to click OK to save the changes.

Method 2: Resize it via command.

1. Open Command Prompt(Admin).

2. Type the following command. It will show you the current maximum usage size for all drives that have a shadow copy storage space.

vssadmin list shadowstorage

3. Type the command below:

vssadmin resize shadowstorage /for=<ForVolumeSpec> /on=<OnVolumeSpec> /maxsize=<MaxSizeSpec>

For example:

vssadmin resize shadowstorage /for=C: /on=C: /maxsize=12GB

 OR

vssadmin resize shadowstorage /for=C: /on=C: /maxsize=5%

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_{Thursday, November 30, 2017 9:57 AM ✅Answered | 1 vote}

Thanks very much – I successfully made a backup now!

I started with method 2 and got the mysterious answer:

Then I successfully used method 1…

:) Søren

_{Thursday, November 30, 2017 9:59 AM ✅Answered}

Hi,

So your issue resolved?

If yes, please mark the helpful reply as answer in order that other community members could find the helpful reply quickly.

If no, please reply and tell us the current situation in order to provide further help.

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_{Friday, December 1, 2017 1:20 AM ✅Answered}

Hi,

Please mark the my reply (include the method 1 works for you) as answer in order that other community members could find the helpful reply quickly.

Please remember to mark the replies as answers if they help.
If you have feedback for TechNet Subscriber Support, contact [email protected].

_{Wednesday, February 20, 2019 9:55 PM ✅Answered}

Just a bit of FYI:

Keep in mind that the vssadmin resize command is a bit misleading. It doesn't actually resize anything, but it sets the maximum size value, so when volsnap comes along later to add more to your snapshot storage, it knows the limit that you have set.

If your disk IO's are high and the volsnap can't allocate space fast enough, it will either 

a) delete your snapshot, which is the default (yes, it really is the default)

b) take the entire volume offline

Unfortunately volsnap is a separate process that doesn't run inline with the IO subsystem, so it is not able to simply "pause" your IO's to complete an actual resize.

To choose your own disaster, whether it deletes or unmounts the volume, you will have to set the protection level on the volume to Snapshot protection instead of OriginalVolume protection, which can be a little challenging to even get to that setting.

If you do really want to resize the volumestorage, there is a nifty trick, you can run this (assume your VSS volume is E: here):

C:> chkdsk E: /C /I

When chkdsk starts up, the first thing it does is extend the shadowstorage to match the MinDiffAreaSize.

I've been trying to figure out that little magical part of chkdsk so I can isolate it and make a utility, but haven't found it yet.