All of the data is an /dev/sda1
What filesystem is this?
ext4
I did a bunch of testing, and after initially thinking I saw an increase it was just due to bad testing because the new TCP_NODELAY changes allowed imaptest to do more work. So I can't see that there is any disk IO difference.
There are a few intentional changes to lib-index and also mdbox code. One of those is that dovecot.index.cache files are being recreated more often now. In some cases they were wasting a lot of disk space because expunged mails hadn't been removed from them. I guess it's a possibility that all the disk IO was because in your system Dovecot started recreating all those files at the same time. Maybe you could try upgrading again during slower hours and see if the disk IO normalizes after a while?
Still running 2.3.7.
Looking at the disk IO graphs today's IO usage looks OK!
I restarted dovecot yesterday after fixing the FTS settings: Jul 16 10:14:45 mail-cbf dovecot: master: Dovecot v2.3.7 (494d20bdc) starting up for imap, lmtp (core dumps disabled)
after that I saw quite a bit of IO on sda1 (a bit of data read, lot of write), which subsided at11:30
After that diskio was low, up to the present day.
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