post-cleanup and preCleanup files in moveChunk directory

[Mark Kwan]

I know the post-cleanup and preCleanup files in the moveChunk
directory are related to data migration between shards. What's not
clear to me (and I don't see it in the docs) are if these files are
supposed to be cleaned up after a successful chunk move. Over 10% of
my disk space is now being used by this directory and most of that
data has a timestamp over a month old. Are those files just there for
logging purposes, or are they still there because something in the
migration process failed? Is there a reason not to delete these
files?

[sridhar]

Mark, the files are not automatically deleted upon moving a chunk. You
can definitely safely delete older files e.g. over a week

[sridhar]

http://www.mongodb.org/display/DOCS/Sharding+FAQ#ShardingFAQ-CanIremoveoldfilesinthe%7B%7BmoveChunk%7D%7Ddirectory%3F

[Markus Gattol]

have a look at http://www.markus-gattol.name/ws/mongodb.html#post-cleanup_or_removedduring

[Mark Kwan]

Ah, I saw your web page Markus, but I missed the point in the Sharding
FAQ that explicitly indicated that they can/should be removed.

So, on error, Mongo will automatically retry and make use of those
files? It's not a manual fixing process like restoring conflicting
data in rollback files?


On Feb 28, 1:54 pm, Markus Gattol <markus.gat...@gmail.com> wrote:
> have a look athttp://www.markus-gattol.name/ws/mongodb.html#post-cleanup_or_removed...

[Scott Hernandez]

On Mon, Feb 28, 2011 at 6:27 PM, Mark Kwan <mark...@gmail.com> wrote:
> Ah, I saw your web page Markus, but I missed the point in the Sharding
> FAQ that explicitly indicated that they can/should be removed.
>
> So, on error, Mongo will automatically retry and make use of those
> files?  It's not a manual fixing process like restoring conflicting
> data in rollback files?

They are mostly used during the moveChunk process but are kept for
redundancy afterwards.

It can be used for manual restoration of moved chunks; I know of a
situation where shard data was lost but they were able to restore the
data that had been moved onto it from other shards using these files.

> On Feb 28, 1:54 pm, Markus Gattol <markus.gat...@gmail.com> wrote:
>> have a look athttp://www.markus-gattol.name/ws/mongodb.html#post-cleanup_or_removed...
>

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