Error using dsync to convert really old mboxes to Maildir and workaround

[Aki Tuomi]

On 24.09.2018 09:10, faginbagin wrote:
> On 9/24/2018 1:50 AM, faginbagin wrote:
>> I ran across what I think may be a bug in dsync when trying to convert from mbox to Maildir format. My first attempt failed with a runaway dsync process spewing out thousands of identical lines of the form:
>>
>> dsync(buus): Error: Duplicate mailbox GUID 00fe691ff60da85b090d0000c8119523 for mailboxes Archive/Personal and Work/VendorInfo - giving a new GUID 00fe691ff60da85b090d0000c8119523 to Archive/Personal
>>
>> These two mail folders happen to be among a number of folders I've had for many years, but also haven't looked at in many years. I used to use UW-IMAP, but switched to dovecot about two years ago, and I'm sure I've never used dovecot to look at those folders. So I suspect the root cause of the above error message was that dovecot had never generated GUIDs for these and some other really old folders.
>>
>> After killing dsync with SIGKILL, which couldn't be killed with SIGTERM, I restored my mbox format Mail folder from backup, restored the mail_location and then coerced dovecot to generate unique GUIDs for all my mail folders with this command:
>>
>> doveadm mailbox status guid `doveadm mailbox list`
>>
>> After the above command, I was able to convert my mail from mbox to Maildir format.
>>
>> Maybe this will help someone else somewhere down the road.
> Forgot to provide dovecot -n output:
>
> # 2.2.27 (c0f36b0): /etc/dovecot/dovecot.conf
> # Pigeonhole version 0.4.16 (fed8554)
> # OS: Linux 4.9.0-8-686-pae i686 Debian 9.5
> mail_location = maildir:~/Maildir
> # mail_location was the following when error occurred:
> # mail_location = mbox:~/Mail:INBOX=/var/mail/%u:UTF-8
> # Also separator was not set when error occurred.
> mail_privileged_group = mail
> namespace inbox {
>   inbox = yes
>   location =
>   mailbox Drafts {
>     special_use = \Drafts
>   }
>   mailbox Junk {
>     special_use = \Junk
>   }
>   mailbox Sent {
>     special_use = \Sent
>   }
>   mailbox "Sent Messages" {
>     special_use = \Sent
>   }
>   mailbox Trash {
>     special_use = \Trash
>   }
>   prefix =
>   separator = /
> }
> passdb {
>   driver = pam
> }
> protocols = " imap"
> ssl_cert = </etc/dovecot/dovecot.pem
> ssl_key =  # hidden, use -P to show it
> userdb {
>   driver = passwd
> }

You could try running doveadm index -u username "*" on the old location
before dsyncing.

Aki