How do I increase default DBD cache size

[Tom Samplonius]

----- "Ramprasad" <ram at netcore.co.in> wrote:
> > No need to patch the code for that - it's an option!  Just put:
> > 
> > berkeley_cachesize: 4096
> > 
> > in your /etc/imapd.conf
> > 
> > We use skiplist for our mailboxes.db and we haven't seen any issues that
> > were caused by leaving that at its default value.
> > 
> 
> I need to compile cyrus with skiplist right ? 
> What are the pros and cons of skiplist ? 


   There is some stuff on the Cyrus website about the recommended database types for the various things that Cyrus needs to know.  Also, read the "install-perf" document in the Cyrus distribution.

  But I really doubt that "berkeley_cachesize" affects skiplist in anyway.



> > That said:
> > 
> > % cat $confdir/db/DB_CONFIG
> > set_cachesize 0 2097152 1
> > set_lg_regionmax 2097152
> > set_lg_bsize 2097152
> > set_lg_max 16777216
> > set_tx_max 200
> > set_tas_spins 1
> > % 
> > 
> 
> 
> I dont have this file in my db directory ( /var/lib/imap/db ) 
> Do I have to create this file ?

  I think it is specific to BerkeleyDB, and created by BerkeleyDB when the environment is initialized.

  You generally can't configure BerkeleyDB.  The application that creates the database sets it up.

..
> > NOTE: we're using reiserfs for our drives, and that machine has 42
> > partitions split over 8 different raidsets via two separate SCSI
> > controllers, and a split meta configuration that puts the meta data
> > on RAID1 for speed.  Still, it's possible to get an order of magnitude
> > more connections out of that sort of spec.  That's 8Gb of memory in
> > that machine, and dual hyperthreading Xeons:
> > 
> 
> Why do you have so many partitions ? And do you run the MTA on the
> same
> machine ? 

  I think at FastMail, they are concerned about filesystem corruption and long fsck times on big filesystems.

  I dislike ReiserFS.  If you run it in parallel with any other logging file system, you'll have plenty of statistical data to show you are fsck'ing ReiserFS more than the other filesystems.


> Thanks
> Ram


Tom