On 09/29/13 06:26, Yonatan Broza wrote: > I'm using tarsnap to backup around 22GB in 22K files. > > There's hardly any difference between backups (verified using diff) yet > tarsnap > reports 12MB of new data. > > Most timestamps are changed since most of the files are recreated before each > backup. > > What's the reason for the large amount of new data?
Tarsnap stores a 512-byte tar header for each file, and this header includes the file modification time. 22,000 files x 512 bytes/file = 11.2 MB, so this looks like the reason for the new data you're seeing. The good news is that tar headers tend to compress very well, so the data you're actually uploading -- the *compressed* new data -- is almost certainly much less than that. -- Colin Percival Security Officer Emeritus, FreeBSD | The power to serve Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid
