problem with cyrus-databases

[Gunther Grelczak]

Hello,

since 2 Years my mailserver is up and running with a self compiled
cyrus 2.1.15 and web-cyradm for administration. Now it very often 
happens that cyrus crashes with his mailboxes.db.

 > ctl_cyrusdb[20562]: DBERROR: critical database situation
 > reconstruct[20565]: DBERROR db4: PANIC: fatal region error detected; 
run recovery

On this page people talk about changing the db-backend from berkely to 
skiplist :
http://asg.web.cmu.edu/archive/message.php?mailbox=archive.info-cyrus&searchterm=fatal%20region%20error&msg=29028

Is it recommended ? Can I do this on the live system by
- stopping cyrus
- changing imapd.conf
- starting cyrus ?????

Does cyrus change the database-format by himself or do I have to run a 
special conversion utility?

My cyrus:

cyrus-imapd-2.1.15
cyrus-sasl-2.1.15
db-4.1.25

It would be great if someone could give me some additional informations 
and a piece of help.

Regards
---
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