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Re: Homedir backup (was Re: "Stateless Linux" project)

Dan Williams wrote:
On Wed, 2004-09-15 at 12:09 -0400, Owen Taylor wrote:

So, you might want to look at it as "backup only when on these
networks". I think it's pretty reasonable to assume that people
have lots of bandwidth at home and at work these days.

Which presents the question, is there any attributes that NetworkManager
can expose about the network that would help this?  Time connected so
far attribute (though that wouldn't really tell you anything about what
the user might do 5 seconds from now when they pull the plug and walk
out of the coffee shop)?

NetworkManager doesn't have a concept of profiles, since that was a
specific exclusion from the beginning (profiles suck).  I'm not quite
sure how to go about a "backup only when on these networks", except
perhaps for these two ideas:

1) on wired networks, use your hostname as returned via DHCP, match that
against a "home network" sort of thing.  But remember, NetworkManager
keeps the hostname of the actual machine constant (because otherwise X
falls over and dies), so NM would save the hostname right before setting
it back and expose that via DBus

2) On wireless networks, we could key off of the ESSID of the base
station to figure out whether you were on a "home" network or not.

3) other, more complicated ways?

I think the way this should work is:

Can I make a _secure_ connection to _my_ server?
(Think ssh connection with the keys set up to know that the other side is who you think it is.)
If so, start the backup process over that link.
Do scheduling of the network traffic so user-initiated traffic gets higher priority than the backup. Keep in mind that the backup may be initiated by the user as well and would need to get scheduled as such.
The user needs a way to tell the system "Don't do that right now" in case they are on an expensive link, or know something else the computer doesn't know, can't know, or misunderstands.
There should also be a user-configurable daemon (or whatever) that can tell the backup system whether it should do its thing right now or not, based on arbitrary factors. For instance: battery life, disk is spun down, we're plugged into power, it's been X hours, we have Y kB of deltas that need to be backed up, certain important files have been modified, etc., etc.

Otherwise, you're confusing "where I am" with "what I can do". Sometimes they correlate, but they aren't really the same.

--------------------. "If it ain't broke now,
Eli Carter           \                  it will be soon." -- crypto-gram
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