[Box Backup] Restoring a corrupted archive?

[Chris Wilson]

Hi Magnus,

On Thu, 1 May 2008, Magnus Homann wrote:

> Chris Wilson wrote:
> 
> > This really should not be happening. Is this all data that you copied from
> > the remote system, i.e. no remnants of your old corrupt local backup? Is it
> > possible that the local copy got corrupted while it was being rsynced?
> 
> Yes, it is possible, even likely, that the archive somehow got corrupted while
> rsynced.
[...]
> > How exactly did your local filesystem get corrupted? Was it user error or a
> > hardware failure? Could bad hardware have been slowly corrupting the local
> > copy?
> 
> I think the controller HW got messed up, the two disks that it handles got
> corrupted.

I'm afraid if your remote copy is badly corrupted then all bets are off. 
About the best I can do is to make it possible to skip files with errors 
during restore.

Box Backup is designed for efficient backups over the Internet, perhaps it 
might be wise to run it directly to the remote server in future? Together 
with regular compares, that should minimise the chances of getting corrupt 
data in your store, and alert you quickly to problems before they become 
fatal.

> > When you say 0xbfd9 is recreated, do you know by what? If it's by 
> > bbstoreaccounts check fix, could you tell me what it outputs when it 
> > does this?
> 
> Yes, by running bbstoreaccounts check fix.
> 
> I don't have a log right now, but in short.
> 
> In phase 2, check diectories... a couple of hundred "File ID xxx has different
> container ID, probably moved".
> 
> In phase 4, fix unattached objects "Recretating missing directory bfd9" amd
> the followed by thousands(?) of "Object xyz is unattached".
> 
> After phase 5 and 6 finish without problems, I get "3225 errors found".
> 
> The same thig repeats if I remove the bfd9 file from the archive and run
> bbstoreaccounst again.
> 
> I hope this helps, or i can send yu more information later today.

I'm very surprised that it would recreate the directory in a way that was 
corrupt. I'd like to investigate this.

Are you available this weekend? I'd be happy to spend some time debugging 
this interactively with you.

> That soime of the fiels went missing I can live with, but I want to get 
> as much as possible. During my operationms, the size of the archive has 
> gone from 211 GB down to about 130 GB, is that bbstoreaccounts check fix 
> work?

It could be that it deleted some corrupt files from the store. I'm quite 
surprised that it would do that, though. Perhaps if you could resync from 
the remote repository and run bbstoreaccounts check fix again to get a 
complete log of the output? Or else run "bbstoreaccounts check" (without 
fix) on the remote copy?

Cheers, Chris.
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