[sugar] Disconnected backups.

[Chris Ball]

Hi,

During the Sugar meeting today we talked about how to handle backup
and restore in the case where there is no school server or network.  
Here are some of our thoughts:

* We should backup journal objects only, possibly with compression.
  The USB disks being used for backup won't be huge, and will want
  to store data from many laptops at once.
  
* But then, what do we do when a user has large jobjects?

* We could use the "favorite" flag, or a new backup flag, to signify
  which jobjects the user would like to back up, and we can try to
  accomodate them.  We probably still need a per-user quota.

* We could signify whether to use a disk as a backup source with
  a "Use for backups" flag when you hover over a removable media
  device in the Journal.  Enabling the flag could touch a ".backup"
  file on the disk, which would signify to future XOs that this
  disk is a backup source.

* We don't think that the user should have to click "backup now";
  when a backup source is inserted, the journal could go ahead and
  start backing up favorite items to it automatically.

* To avoid having it show jobjects from other users when you click on
  a removable disk that is a backup source, it could use the /<UUID>/
  directory on the disk as a store for both backups and restores for
  each user, where the UUID is whatever public unique ID we prefer to
  use.

* So how do restores work?  We limit to the /<UUID>/ directory on the
  disk, and let you see those jobjects on the backup disk just as you
  normally would when clicking on a USB disk in the Journal.  You can
  drag individual items over to your NAND, or click a "restore all"
  button that will copy over everything.

* Encryption/privacy probably isn't desirable here -- we're dealing with
  objects that the user has chosen to have backed up.  Also, this would
  provide a good way for kids to turn in homework to their teachers: the
  teacher passes around a USB key, and as each child inserts the key,
  their homework gets automatically copied over to a directory named
  after them if it's marked favorite.

This hasn't gone through Eben or UI design yet, so the next step is to
think about how to make this fit with the rest of the interface.  It
would also be good to have some consensus from the deployment team that
this (backups without a school server) is something that's going to be
needed and is worth spending time on.

Any other thoughts?

Thanks,

- Chris.
-- 
Chris Ball   <cjb at laptop.org>