prepare git lfs intro

git-lfs.md

+# git-lfs
+
+## Is it for me?
+Large (especially binary) files in project you want to track via git.
+
+- researchers with (result) data sets (but …)
+- web designers (pictures)
+
+
+## Why git lfs?
+- big blobs problematic in git
+- each commit creates new tree of objects
+- reuses unmodified objects
+- delta compression on modified objects
+
+https://www.youtube.com/watch?v=iJ3hXuEVKAc
+./img/Tracking\ huge\ files\ with\ Git\ LFS\ -\ LinuxCon_2.pdf
+
+
+## Why git lfs?
+- delta compression does not work well for binary blobs
+- e.g. change colour of image, the whole blob changes
+
+## Solution?
+- git lfs does stores big blobs outside of your repo
+- git lfs stores references to those blobs in repo
+
+## Me needs blobs not the references!
+- git checkout repo as usual
+- git lfs fetch the blobs of your current branch tip
+
+## How do I?
+- `git lfs install` # is global
+- specify which blobs `git lfs track "*.jpeg"`
+- git add cat.jpeg
+
+## smudge and clean filter
+- are set up when git lfs is installed
+- clean converts blobs in pointers
+- smudge converts pointers in blobs 
+- all done in background
+- if you only want to download blobs on request you need --skip-smudge
+
+## authentication
+It should work even if git repo and lfs store are not connected using the client as proxy.
+
+
+## convert
+- old: bfg repo-cleaner
+
+