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Western Digital makes an automatic backup tool called SmartWare. When I tested it out and backed up just a couple of directories from a Windows machine, it works great - except that files taking up 2.5GB of disk space on my C: drive somehow grows to nearly 30GB of physical space on the networked MyBook Live disk.

A 131MB PSD file takes up 132MB of disk space on the MBL, and a 738 byte text file is listed as taking up 1MB.

Does this mean the cluster size of the MBL is really 1MB? If so, is there a way to change it?

nikobelia
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  • I think you are trying to solve a problem with a solution that isn't connected. 2.5GB of files shouldn't take 30GB of space that is a 12x difference. What is the current sector size of the drive? – Ramhound Jan 30 '15 at 12:10
  • You mean the drive isn't the problem? That's useful info if so, thanks. The sector size on the drive I'm migrating data from is 512 bytes, but I can't see a way to check the sector size on the MyBook Live. None of the config pages contain that information. – nikobelia Jan 30 '15 at 12:19
  • I am saying the reason 2.5GB of data takes up 30GB isn't because of the sector size or cluster size. – Ramhound Jan 30 '15 at 12:32
  • OK, cheers. I'll investigate! – nikobelia Jan 30 '15 at 12:42

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Sector size is a fixed feature of a given storage medium; it's not alterable in software. Cluster size can be changed, within limits set by partition format and size, but it's always a multiple of the physical sector.

The problem you describe is most likely due to your backup medium having a very large cluster size, such that tiny files take up one (large) cluster each, but that should also be happening on any uncompressed hard disk or SSD, such as your original drive or partition. You might try another backup solution, perhaps one that creates a sector-by-sector image ("partition image") of the data to be backed up; that type should produce a backup identical in size to the partition being backed up (some might be smaller, because they skip empty space). Another option is compressed backups, which use lossless data compression on the backup data, as well as free space elimination, to make the backup (usually) much smaller than the original.

Zeiss Ikon
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  • Interesting, thanks. So Windows thinks the files take up 2.3GB of space on the C: drive, and this WD Smartware tool claims they're talking up 2.57GB on the backup medium. I guess that means Smartware is reading file size not how many clusters are being used? – nikobelia Jan 30 '15 at 12:38
  • Correct. But your 2.57 GB of files are taking (by report) 30 GB of physical space because they're averaging about 1/12 of a cluster. – Zeiss Ikon Jan 30 '15 at 13:14
  • The maths works out pretty exactly looking at the actual figures :) thank you for teaching me a new thing. – nikobelia Jan 30 '15 at 13:32