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Accumulo >> mail # user >> METADATA recovery


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Re: METADATA recovery
When you have a namenode failure and you recover with teh Secondary
Namenode info, you're dealing with one level of potentially expired
pointers. On top of that, you have more layers of pointers WRT the root
tablet and !METADATA tablets. You can make attempts to recover, but what is
more apt to happen is you'll get a Root tablet up that has some, but not
all of the current !METADATA table files. And then the ones you get do get
up may or may not be pointing to the existing files for your tablets.

What I'm ultimately trying to say is that you already lost some files, you
are more apt to lose more by trying to recover your old information instead
of taking what you have and starting over. I would suggest taking your
accumulo directory, moving it to accumulo_old or something along those
lines, reinstantiate an instance, and begin bulk importing the remaining
old information back into the new system.

John

On Sat, Aug 18, 2012 at 11:08 PM, Denis <[EMAIL PROTECTED]> wrote:

> Hi.
>
> I have a trouble with my Accumulo installation.
> After hardware failure on NameNode, !METATABLE's root_tables is broken :(
>
> From "fsck /" output:
> ....
> /accumulo/tables/!0/root_tablet/A000ornd.rf: CORRUPT block
> blk_-8590712379082603283
> /accumulo/tables/!0/root_tablet/A000ornd.rf: MISSING 1 blocks of total
> size 896 B..
> ....
>
>
> What could you recommend to recover the data?
> Is it possible to reconstruct !METATABLE's root_tablet based on the
> rest of !METATABLE files ?
> Or is possible to reconstruct the whole !METATABLE based on th content
> of the all found tablets ?
> Are there any ready tools to do it ?
>
> Thanks.
>