docs: data migration

[Michael]

http://docs.kolab.org/administrator-guide/upgrading-from-kolab-2.3.html#migration-of-ldap

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Ensure only the cyrus user can read and write, and the mail group can read the contents of either directory tree:

# find /var/lib/imap -type f -exec chmod 640 {} ;
# find /var/lib/imap -type d -exec chmod 750 {} ;
# find /var/spool/imap -type f -exec chmod 640 {} ;
# find /var/spool/imap -type d -exec chmod 750 {} ;
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first: copy&paste into shell won't work, '{}' ';' should be escaped or quoted.

second: This will fork a new chmod-process for every single mail in the mail store.

At my little ARM-SoC-Board and a mail store of more than 100.000 mails I aborted this after waiting some minutes. It felt like waiting forever... at least for the spool directory.

Then I did:
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# find /var/spool/imap -type f -exec echo chmod 640 '{}' '+'
# find /var/spool/imap -type d -exec chmod 750 '{}' '+'
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and it completed after some seconds. Using "-exec command {} +" (man find) or "chmod -R" is much faster for larger mailboxes.

btw. is it ok to pollute the mailing list with such things?

Regards
Michael