[ext] Re: dovecot 2.3.7.2-1~bionic: Performance issues caused by excessive IO to ~/mdbox/mailboxes/INBOX/dbox-Mails/dovecot.index.tmp

[Ralf Hildebrandt]

> > This command quickly pointed to ~/mdbox/mailboxes/INBOX/dbox-Mails/dovecot.index.tmp
> > That file was written excessively. 
> 

> Was it one user's dovecot.index.tmp or for a lot of users?

There's just one user. All mail goes to one mailbox.

> This
> means that dovecot.index is being rewritten, which should happen only
> once in a while, but now it sounds like it's happening maybe for every
> mail delivery.

Yes, it seems to be that way.

> If it's still happening, could you send me one folder's
> dovecot.index and dovecot.index.log files? (They don't contain
> anything sensitive other than maybe message flags.)

I can send the files.

> > This is dovecot 2.3.7.2-1~bionic
> 
> So you had been running this version already for a while, and then it just suddenly started getting slow?

Yes. Initially I threw away the whole mailbox after it got slow, but
after a few days the performance started to degrade. Admittedly, it
contains a lot of mails :)

> I tried to reproduce this with imaptest and Dovecot that is patched
> to log when dovecot.index is being rewritten, but there doesn't seem
> to be any difference with v2.2.36, v2.3.7 or git master.
 
-- 
Ralf Hildebrandt
  Geschäftsbereich IT | Abteilung Netzwerk
  Charité - Universitätsmedizin Berlin
  Campus Benjamin Franklin
  Hindenburgdamm 30 | D-12203 Berlin
  Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962
  ralf.hildebrandt at charite.de | https://www.charite.de