[Box Backup] Network failure

[Ben Summers]

On 6 Feb 2005, at 12:27, Mr R G Shepherd wrote:

> Dear list,
>
> I am exceedingly interested in using boxbackup.
>
> However I would like to evaluate it's resillience for
> numerous outages, disasters and anomolies.
>
> Has anybody had experience with a network outage or connectivity blip
> during a backup? can the server side be corrupted easily?

Since backups are potentially long operations, the server is written to 
expect problems to occur.

Every file write is performed in a transactioned manner, so either the 
file is written successfully or the store is not changed at all. Also, 
where entities are written lazily to increase performance, there is 
recovery code to cope with this data being out of date. (And all 
important data is committed immediately it is completely available.)

If the worst should happen, there is a utility to check a store and 
rebuild it. This will make all valid data in the store available, 
whether it is in the directory structure or not.

The client is written to be conservative about assuming server state, 
and will re-query and compare if it detects a problem.

I suggest you give it a go! Set a long backup going, then at random 
intervals kill the server and client, and pull out network cables. Then 
report back to the list.

Ben