Adjusting Timemachine size on ReadyNAS Duo

I have a ReadyNAS Duo, and several Mac devices backing up to it (via the typically “Apple awesome” Time Machine feature).

I recently upped the allocated disk space in FrontView to 300GB, from 120GB – which while each Mac’s Time Machine preferences said “NAS device, 300GB” – claimed the disk didn’t have enough “temporary space” to perform the backup.


I got SSH access to the ReadyNAS working – (I used Enable SSH plugin), and took a look around the filesystem.

It appears in classic OSX style, Apple have opted for a simple .plist info file:

cat /c/.timemachine/Matthew\ Hall’s\ MacBook.sparsebundle/Info.plist

Upping the value to the match the new disk size (300*1024*1024*1024), solved the issue.

Presumably (speculation) OSX treats the .sparsebundle directory as a disk image – and the Info.plist defines how “big” the disk image is – even though its a directory (can anyone confirm?). Thus the “disk” was indeed 300GB, but the existing backup image was only 100GB …

Shame Netgear / Apple didn’t put something obvious to allow updating the .plist file, but never mind! Problem solved …

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