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Re: best practices WRT resizing a MDB backend?
On Thu, Aug 21, 2014 at 03:28:42PM -0700, Howard Chu wrote:
> maxsize is the back-mdb keyword. mapsize is the LMDB API property. They
> both refer to the same thing. We used the word "maxsize" for back-mdb to
> impress upon sysadmins that this really is a long-term maximum, and not a
> setting that should be tuned on an ongoing basis.
Ok, that explains the terminology.
> >Can 'maxsize' ever be reduced after the fact? If so, is their
> >guidance as to how much it can change (perhaps based on mdb_stat)?
> Read the LMDB documentation.
What, this: http://symas.com/mdb/doc/ ?
A search for 'maxsize' or 'mapsize' yeilds no hits.
The mdb_stats manpage tells me how to invoke it, but not how to
interpret the results. I have seen other messages to this mailing
list provide some guidance, but nothing that seemed to directly
apply to my questions. Perhaps I'm missing some keyword somewhere.
> >My naive use of the LDMB backend has me assume the worst case, and
> >now everyone is equally punished for having a 'big' (albeit sparse)
> "Punished"? There is no penalty for configuring a large maxsize, no matter
> how small the actual data.
The 'punishment' is multifold:
- consumption of diskspace for storage (our database is stored on
the same partition as our backups; perhaps not the best of plans).
- the time it takes to compress/uncompress a backup.
- the network bandwidth cost of transmitting a file that's larger than
it needs to be.
> -- Howard Chu
> CTO, Symas Corp. http://www.symas.com
> Director, Highland Sun http://highlandsun.com/hyc/
> Chief Architect, OpenLDAP http://www.openldap.org/project/
Brian Reichert <firstname.lastname@example.org>
BSD admin/developer at large