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One of the partitions on our Server 2003 R2 server recently ran out of free disk space.

After freeing up a significant amount of free space (20 GB, which only corresponds to 1.37% of the partition - maybe not enough?), I noticed that the "Compress contents to save disk space" option was greyed out for every file and folder on that partition:

enter image description here

Does there need to be a certain percentage of free space on the drive, rather than absolute amount of free space? Or maybe running out of free space caused it to disable this option and it won't return until the system is rebooted?

Just to clarify: this option used to exist on this partition at one point and the partition was, and still is, NTFS formatted. All other NTFS partitions on this drive do have a "Compress drive to save disk space" option in the "General" tab but that option does not exist for this particular partition.

I haven't seen this before and couldn't find any information online about it.

Does anyone have any idea what could cause this to happen and how can go about fixing it?

Community
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Austin ''Danger'' Powers
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1 Answers1

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What is the cluster size? NTFS compression only works on volumes with a cluster size of 4k or less.

http://blogs.msdn.com/b/ntdebugging/archive/2008/05/20/understanding-ntfs-compression.aspx

Native NTFS compression does not function on volumes where the cluster size is greater than 4KB, but sparse file compression can still be used.

jimp
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  • Good one... Especially since he mentions that it is a HUGE volume. – Tonny Jun 10 '15 at 14:01
  • But normally the cluster-size isn't changed and it used to work before. Could be someone used fsutil to disable compression. (Do "fsutil behavior query disablecompression" to check that.) Check clustersize with "fsutil fsinfo ntfsinfo ". – Tonny Jun 10 '15 at 14:10
  • 20 GB as 1.37% of the total is only a 1.5 TB partition. https://support.microsoft.com/kb/140365 The default cluster size is 4k up to 2TB, but I agree it's not common to change it later. – jimp Jun 10 '15 at 14:13
  • This server is virtualized - maybe I should've mentioned it before but I wasn't sure if it was relevant. Does cluster size matter with VMs the same way as with physical machines? – Austin ''Danger'' Powers Jun 10 '15 at 14:20
  • I do not think that should matter. Checkout of that MSDN link above. There is a screen shot that looks like yours with the checkbox grayed out due to a sparse file getting copied manually. Perhaps your issue is related. I'm sorry, I really don't know why yours is happening. I did some searches and didn't turn up much else. – jimp Jun 10 '15 at 15:05
  • You might want to mention 4k clusters are not possible on 18+ terabyte drives, would have saved me 4 weeks of trouble emptying and refilling. – Bricktop May 17 '23 at 11:41