Question about using this for backing up a file that changes daily

[Automatic Coding]

Basically, I have a file that I want to backup daily, it's 8GB on the dot and will never change (and if it does, then I'm happy to wait a bit of extra time because for said file to change requires a hell of a reason and won't happen often), I want to back it up once a day for at-least 7 days before starting to overwrite it, so, I have a command that backs it up to:-

When backup is made:-

myTotallyAwesomeBackup1.

After day one it's renamed to:-

myTotallyAwesomeBackup2

After day two it's renamed to:-

myTotallyAwesomeBackup3

[...]

After day six it's renamed to:-

myTotallyAwesomeBackup7

After day seven it's deleted.

However, I have a few questions about this and ease-of-transport. The internet of the back-up machine isn't the best (Under 1MB/s) so I'd prefer not to be pulling 8GB files down per day. So, my first idea was to add a compression part to the script, however, once I attempted to add it in I noticed how different the file is compared to how different the original file is. I'm not sure if it's a simple data "Shift" or if the whole compression really is different (never looked into how compression works too be honest). As shown below is two files from two different days before/after syncing with their size and changed bytes:-

Unencrypted:-

7.5G CompressTestOne
7.5G CompressTestTwo
40199404 bytes (38MB)

Encrypted (Only tested up until test two EOF'd, the excess data was excluded from tests):-

779M CompressTestOne.gzip
748M CompressTestTwo.gzip
781130671 bytes (744 MB)

Basically, my question is, is there anyway to compress a file without changing the whole file when it changes daily?

Although, once bittorrentsync supports compression during transmission then this is all pointless.

[kos13]

Sync doesn't yet use compression. You need to tet what will be better sending 744MB or just the difference of original files. IT has a very high chances that difference of original files will be smaller.

[johnmarshall4]

Sync doesn't yet use encryption.

:| I think you mean Sync doesn't yet use 'compression'.

[kos13]

:| I think you mean Sync doesn't yet use 'compression'.

Sure Corrected.