catastrophic recovery required

[Ben Finney]

Thanks for the ongoing assistance.

On 16-Feb-2005, Matthias Andree wrote:
> OK. My scoop of this is:
> 
> 1. Berkeley DB uses database pages that are larger than hard disk drive
>    blocks.
> 
> 2. No Linux file system and device driver in production quality and
>    default settings guarantees atomic writes of Berkeley DB pages.
> 
> 3. ext3fs with data=journal mount option SHOULD be able to write memory
>    page size (4k) atomically AFAIR.

I'm using ext3, with no particular options fiddling.  I thought the
point of a journalled filesystem was that *all* data writes are atomic?
What do I have if I'm not using the "data=journal" option?  (URLs with
answers to these questions are welcome.)

> 6. db-prune runs caused the removal of inactive log files, rendering
>    catastrophic recovery impossible.
> 
> 7. If however you have kept backup copies of your logfiles, put them
>    into your .bogofilter directory and run
>    "bogoutil --db-recover-harder ~/.bogofilter"

My understanding was that, since 'bogoutil --db-prune' gave no errors,
my data was safe.  Backups were kept at one time, but removed once it
was clear to me that 'bogoutil --db-prune' was an atomic operation.

> Did you disable the write caches as laid out in README.db? If you did
> not, that may have been the cause for the troubles you're witnessing.
> I suggest disabling the write caches if you have flakey power supply.

I don't have a flakey power supply, but like all power systems (even
ones in well-provisioned grids) it is vulnerable to lightning storms.

> At any rate, check the README.db revision I posted on 2005-02-05 for
> recovery procedures.

Shall do.  Thanks again.


On 16-Feb-2005, Tom Anderson wrote:
> And for goodness sake, get a UPS ;)

My UPS has a dead battery, and I won't have the cash to buy another for
quite a while.

-- 
 \       "The Stones, I love the Stones; I can't believe they're still |
  `\      doing it after all these years. I watch them whenever I can: |
_o__)                             Fred, Barney, ..."  -- Steven Wright |
Ben Finney <ben at benfinney.id.au>
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