Disk might be cheap, but my /home is always full -
git has a separate step for compacting repositories, which
means that delta compression can be far more effective. If
you're a compression buff, think of it as having an arbitrarily
sized window, because when delta compressing git is able to match
strings anywhere else in the repository - not just the file
which is the notional ancestor of the new revision.
This space efficiency affects everything - the virtual memory
footprint in your buffercache while mining information from the
repository, how much data needs to be transferred during "push" and
"pull" operations, and so on. Compare that to Subversion, which
even when merging between branches is incapable of using the same
space for the changes hitting the target branch. The results speak
for themselves - I have observed an average of 10 to 1
space savings going from Subversion FSFS to git.