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List:       amanda-hackers
Subject:    Re: Incorrect bahaviour causes backup loss !!
From:       Matthias Andree <matthias.andree () gmx ! de>
Date:       2006-07-27 21:14:20
Message-ID: m3lkqeiwcz.fsf () merlin ! emma ! line ! org
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Jon LaBadie <jon@jgcomp.com> writes:

> On Thu, Jul 27, 2006 at 04:07:40PM +0100, Alan Pearson wrote:
>> NOTES:
>>   planner: Last full dump of qtvpdc:/ on tape DailySet1-3 overwritten on this run.
>>   planner: Incremental of qtvpdc:/ bumped to level 2.
>>   planner: qtvpdc / 20060727 0 [dump larger than available tape space, 35448530 KB, full dump delayed]

>> In the NOTES section it says that a full dump of the machine qtvpdc  
>> was delayed because it was larger than available tape space.
>> Yet it says it is going to overwrite the last full dump of this  
>> machine 2 lines previous.
>> 
>> Yes I realise it wouldn't fit on the tape, but Amanda should at least  
>> have put it in the holding disk area or NOT overwritten the only full  
>> backup at all.
 
> That would seem to be a hard call.

The planner runs BEFORE anything happens to the tape, right?
(After all it needs to plan the dump levels.)

I've also been in the situation where amanda would happily kill the last
full dump. So why in hell are *again* excuses made for for a *FATAL*
mistake of Amanda's planner? The minimum fix would be pretending the
slot were empty and going to degraded mode. Oh, and add to that: tar
(GNU tar) 1.15.1 will happily overestimate sparse files and think it has
4 GB to stuff when it has in fact only 2.8 GB...

In my case, the configuration was f*cked up (check the archives),
without amanda sanity checking them and printing a gentle warning.

> For just one example, I've got a DLE that I only do weekly full dumps,
> no incrementals.  It contains nothing but *.iso files, dvd or cd
> images, that I can easily recreate from the original optical media.

Excuse me, who cares for *your* backing up garbage?

> And some of my DLEs go directly to tape, bypassing the holding disk.
> Should the backup of those direct to tape DLEs be skipped to preserve
> my relatively unimportant last full dump of the *.iso DLE?

There are priorities in the dump definitions that can aid in making this
decision - if the priority of the level 0 dump to be killed is higher
than the data you're dumping directly to disk, lock the tape out.

> Just for info, how did you get to the situation of only having one
> full dump in the tapecycle?  If that tape failed you would have
> been in a similar situation.

Yes, but that's not a deliberate loss of data, unlike Amanda overwriting
things (even though overwriting the last level 0 is a bad idea anyways).

> Failed tapes were pretty common for me when I was using DDS tapes.

It's known that DDS tapes like all helical scan media are consumables
and stand only a few dozen cycles.

> Typically I have 3-5 full dumps within a tapecycle.  (Not counting
> those in the archive config)

So, is that permission to deliberately destroy the *LAST* one?
I think not.

-- 
Matthias Andree
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