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On many different servers running many different versions of Windows Server we use AhsayOBM to backup to cloud and USB-connected external HDDs which generally has no problems.

However, one server running Windows SBS 2011 and AhsayOBM version 7.7.0.0 has a problem whereby the backup of system image to the USB-connected external HDD fails as there is not sufficient storage capacity available.

The affected HDD's:

  • Total storage capacity: 931 GiB
  • Reported available storage capacity: 321 GiB
  • Reported storage usage: 610 GiB
  • Actual storage usage: ~337 GiB

So, this doesn't add up - there is ~273 GiB of storage usage unaccounted for / missing, as verified by WinDirStat running as administrator.

Interestingly, the same thing happened even when we replaced the HDD with the same model.

Screenshots:

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Update 2016/11/08 10:03 in response to Wraezor Sharp's comment:

Previous versions / Shadow Copy is not enabled on the affected drive / volume.

Screenshots:

enter image description here enter image description here

 

Update 2016/11/09 09:12 in response to Wraezor Sharp's answer:

WinDirStat running as SYSTEM reports the same:

enter image description here

Windows SBS 2011 doesn't have System Protection options:

enter image description here

mythofechelon
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  • Do you have Previous Versions enabled? The "System Volume Information" folder is probably not empty, but rather inaccessible to your user account. It is quite likely that is where the 'missing' data is. – Wraezor Sharp Nov 07 '16 at 16:59
  • @WraezorSharp Please refer to update 2016/11/08 10:03. Thanks. – mythofechelon Nov 08 '16 at 10:03

2 Answers2

1

The unaccounted storage usage was indeed Shadow Copy, despite Windows consistently reporting that it is disabled.

Elevated command vssadmin list shadowstorage reported the following:

vssadmin 1.1 - Volume Shadow Copy Service administrative command-line tool
(C) Copyright 2001-2005 Microsoft Corp.

Shadow Copy Storage association
   For volume: (\\?\Volume{d93bd5c8-7061-11e2-92bb-806e6f6e6963}\)\\?\Volume{d93
bd5c8-7061-11e2-92bb-806e6f6e6963}\
   Shadow Copy Storage volume: (\\?\Volume{d93bd5c8-7061-11e2-92bb-806e6f6e6963}
\)\\?\Volume{d93bd5c8-7061-11e2-92bb-806e6f6e6963}\
   Used Shadow Copy Storage space: 0 B (0%)
   Allocated Shadow Copy Storage space: 0 B (0%)
   Maximum Shadow Copy Storage space: 32 MB (32%)

Shadow Copy Storage association
   For volume: (E:)\\?\Volume{6d48b478-7105-11e2-a9f6-000c29c784ef}\
   Shadow Copy Storage volume: (E:)\\?\Volume{6d48b478-7105-11e2-a9f6-000c29c784
ef}\
   Used Shadow Copy Storage space: 184.148 GB (9%)
   Allocated Shadow Copy Storage space: 187.046 GB (9%)
   Maximum Shadow Copy Storage space: 204.799 GB (10%)

Shadow Copy Storage association
   For volume: (F:)\\?\Volume{21b9cb82-cc4f-4cbc-991c-e5490c15ae46}\
   Shadow Copy Storage volume: (F:)\\?\Volume{21b9cb82-cc4f-4cbc-991c-e5490c15ae
46}\
   Used Shadow Copy Storage space: 270.343 GB (29%)
   Allocated Shadow Copy Storage space: 272.648 GB (29%)
   Maximum Shadow Copy Storage space: 279.444 GB (30%)

Shadow Copy Storage association
   For volume: (C:)\\?\Volume{d93bd5c9-7061-11e2-92bb-806e6f6e6963}\
   Shadow Copy Storage volume: (C:)\\?\Volume{d93bd5c9-7061-11e2-92bb-806e6f6e69
63}\
   Used Shadow Copy Storage space: 46.36 GB (9%)
   Allocated Shadow Copy Storage space: 47.309 GB (9%)
   Maximum Shadow Copy Storage space: 49.989 GB (9%)

enter image description here

The drive's / volume's tab "Shadow Copy" reported that Shadow Copy was disabled but using 279832 MB.

enter image description here

Reducing the Shadow Copy usage to the minimum 320 MB resolved the problem.

enter image description here

enter image description here

mythofechelon
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0

The missing data is almost certainly in the "System Volume Information" folder. By default, you do not have access to see the contents or size of that folder. If you grant yourself permission to it, so you can see the true size, you will likely find that it is quite large. See: https://support.microsoft.com/en-ca/kb/309531

That folder is used for a few things. It is not recommended to delete files from it directly. Various Windows settings should be adjusted to reduce its size. Here is a list: https://blogs.msdn.microsoft.com/oldnewthing/20031120-00/?p=41753/

One of the biggest space culprits is Restore Points. To disable restore points, open the System panel in Windows, then click "System Protection" Ensure that protection is either "Off" for the disk, or at very least, limit them in size to a reasonable percentage (perhaps 5-10%).

Wraezor Sharp
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