git for cluster sync over ssh: on kqueue, add, commit, push, merge.
Use a kqueue watcher service to trigger gtfc-push if files have changed.
There's an example in gtfc-watch which launches gtfcwatch.py
| Property | Description |
|---|---|
| Centralized aspect | Only the first node with unique/latest data will be central until it completes a push. |
| Decentralized storage | Yes. When all nodes are up to date, there is no central store because git repositories are mirrors. Akin to RAID1 mirror, but not to RAID5 span. |
| Distributed storage | No, files are not split/striped across nodes. |
| Decentralized/distributed transfers | Yes. Nodes can push to any other nodes. |
| Chunked data transfers from multiple hosts | No. |
| Security? | Pretty good, but only as good as your SSH config. |
| Optimal use | Good for small files, best with text. |
| Limitations | Bad for large files or binary. Sync based on git commits, not files. Since we use authorized_keys2 to let peers in, make sure to have different users for different repos if you need to restrict peers. |
local$ ssh alpha
alpha$ gtfc-bootstrap ~/myrepo
local$ ssh -A beta
beta$ gtfc-join alpha ~/myrepo
alpha$ echo `date` `hostname` > ~/myrepo/test
alpha$ gtfc-push
You probably want to pull changes at boot or in a boot script.
beta$ gtfc-pull
alpha$ gtfc-watch
beta$ gtfc-watch
Yes. Since the we force a command on ssh connections, we can just use a gtfc-shell that doesn't allow receiving a push.
Set the command in authorized_keys2, replacing gtfc-shell with gtfc-shell.denywrite
lsyncd + rsync (which deletes the file without keeping history)