[Box Backup] Thoughts on reliability (Was: "Box Backup - corrupted store")

[Gary]

Ben,

> I suspect that in this case of corruption, a block got corrupted  
> somehow after it was committed.

> Berkeley DB is only used on the client to track non-essential data.

My bad, I have not looked at the server sources that deep, yet. At any
rate, how does the server side guarantee consistency in case of an
interrupted upload or interrupted server-side file write (especially
for large files)?

> It compares MD5 checksums of each block with the index. Using a hash 
> is good enough for digital signatures, so I hope it's good enough for
> this.

> I suppose a MD5 of the encrypted data could be kept as well, and the 
> server could verify that the file is still OK?

There seem to be two separate issues here: comparing server index
content with client content (-q), and verifying that server index
content is actually what is on a server hard drive. The first issue has
already been solved by comparing current client content blocks with
last known uploaded blocks on the server (index), right? The second
issue is currently not implemented, but, if I understand correctly, if
a function is added to make sure that the server side index is actually
what's currently on the server hard drive, then a complete end-to-end
compare has been achieved.

I guess we would need some kind of "association" of reported client
blocks (index content) with factual server content.

Did I get this right?

Gary



		
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