dovecot - Jun 2015 - Questions about hardlinks, alternate storage and compression

Hi all,
I have some questions about hardlinks, alternate storage and 
compression. I already scanned the list for related information and I 
have an idea of how things works, but I would like to have a definite 
answer.

System spec:
- CentOS 6.6 x64
- dovecot-2.0.9-8.el6_6.4.x86_64 RPM package/version
- sdbox mail store

1) About hardlinks: when sending the same message to two different 
recipients, I see that the two u.x files are created as two different 
files. Diffing them, I see that the only difference is a single char 
(see [1] for an example). My questions are:
   a) it is possible to tell dovecot to create a single file + a single 
hardlink (linkref=2)? As other IMAP servers support that features (eg: 
Cyrus, CommunigatePro, etc) I am wondering if I missed something in 
configuring dovecot...
   b) If it is not possible, can I run a script that compare the various 
files and substitute equal ones (minus the changing line) with 
hardlinks, or it will confuse dovecot? As a side note, why the changing 
line ever exists?

2) About alternate storage and compression: actually, I use a single 
mail_location without compression. I would like to have an alternate 
storage and to enable compression on it only, leaving the main location 
without compression. I if understand it correctly, it _should_ be done 
using a command similar to "doveadm -Dv -o "plugin/zlib_save=gz"
altmove
-uu testuser sentbefore 8d". I'm right thinking that it should work? I 
will really end with a primary uncompressed mail store and an alternate, 
zlib-compressed one?

Thank you all and sorry if I did some naive questions.

[1]
63c63
< G2fd0811c64be8e553d970000eaa8309f
---
> G2ed0811c64be8e553d970000eaa8309f


-- 
Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it
email: g.danti at assyoma.it - info at assyoma.it
GPG public key ID: FF5F32A8

Hi all,
any ideas?

Especially point n.1 (no hardlink when sending the same email to 
multiple addresses) confuse me a bit. Searching in old messages I even 
stumbled on some users stating that, using Dovecot LMTP server, they 
achieved what I want (one messagge, multiple hardlinks), but I am 
_already_ using LMTP with no avail...

Regards.

On 27/06/15 18:18, Gionatan Danti wrote:
> Hi all,
> I have some questions about hardlinks, alternate storage and
> compression. I already scanned the list for related information and I
> have an idea of how things works, but I would like to have a definite
> answer.
>
> System spec:
> - CentOS 6.6 x64
> - dovecot-2.0.9-8.el6_6.4.x86_64 RPM package/version
> - sdbox mail store
>
> 1) About hardlinks: when sending the same message to two different
> recipients, I see that the two u.x files are created as two different
> files. Diffing them, I see that the only difference is a single char
> (see [1] for an example). My questions are:
>    a) it is possible to tell dovecot to create a single file + a single
> hardlink (linkref=2)? As other IMAP servers support that features (eg:
> Cyrus, CommunigatePro, etc) I am wondering if I missed something in
> configuring dovecot...
>    b) If it is not possible, can I run a script that compare the various
> files and substitute equal ones (minus the changing line) with
> hardlinks, or it will confuse dovecot? As a side note, why the changing
> line ever exists?
>
> 2) About alternate storage and compression: actually, I use a single
> mail_location without compression. I would like to have an alternate
> storage and to enable compression on it only, leaving the main location
> without compression. I if understand it correctly, it _should_ be done
> using a command similar to "doveadm -Dv -o
"plugin/zlib_save=gz" altmove
> -uu testuser sentbefore 8d". I'm right thinking that it should
work? I
> will really end with a primary uncompressed mail store and an alternate,
> zlib-compressed one?
>
> Thank you all and sorry if I did some naive questions.
>
> [1]
> 63c63
> < G2fd0811c64be8e553d970000eaa8309f
> ---
>> G2ed0811c64be8e553d970000eaa8309f
>
>
>
-- 
Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it
email: g.danti at assyoma.it - info at assyoma.it
GPG public key ID: FF5F32A8

Sorry list,
anyone with a good idea / suggestion?

Thanks.

Il 29-06-2015 11:20 Gionatan Danti ha scritto:
> Hi all,
> any ideas?
> 
> Especially point n.1 (no hardlink when sending the same email to
> multiple addresses) confuse me a bit. Searching in old messages I even
> stumbled on some users stating that, using Dovecot LMTP server, they
> achieved what I want (one messagge, multiple hardlinks), but I am
> _already_ using LMTP with no avail...
> 
> Regards.
> 
> On 27/06/15 18:18, Gionatan Danti wrote:
>> Hi all,
>> I have some questions about hardlinks, alternate storage and
>> compression. I already scanned the list for related information and I
>> have an idea of how things works, but I would like to have a definite
>> answer.
>> 
>> System spec:
>> - CentOS 6.6 x64
>> - dovecot-2.0.9-8.el6_6.4.x86_64 RPM package/version
>> - sdbox mail store
>> 
>> 1) About hardlinks: when sending the same message to two different
>> recipients, I see that the two u.x files are created as two different
>> files. Diffing them, I see that the only difference is a single char
>> (see [1] for an example). My questions are:
>>    a) it is possible to tell dovecot to create a single file + a 
>> single
>> hardlink (linkref=2)? As other IMAP servers support that features (eg:
>> Cyrus, CommunigatePro, etc) I am wondering if I missed something in
>> configuring dovecot...
>>    b) If it is not possible, can I run a script that compare the 
>> various
>> files and substitute equal ones (minus the changing line) with
>> hardlinks, or it will confuse dovecot? As a side note, why the 
>> changing
>> line ever exists?
>> 
>> 2) About alternate storage and compression: actually, I use a single
>> mail_location without compression. I would like to have an alternate
>> storage and to enable compression on it only, leaving the main 
>> location
>> without compression. I if understand it correctly, it _should_ be done
>> using a command similar to "doveadm -Dv -o
"plugin/zlib_save=gz"
>> altmove
>> -uu testuser sentbefore 8d". I'm right thinking that it should
work? I
>> will really end with a primary uncompressed mail store and an 
>> alternate,
>> zlib-compressed one?
>> 
>> Thank you all and sorry if I did some naive questions.
>> 
>> [1]
>> 63c63
>> < G2fd0811c64be8e553d970000eaa8309f
>> ---
>>> G2ed0811c64be8e553d970000eaa8309f
>> 
>> 
>> 
-- 
Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it
email: g.danti at assyoma.it - info at assyoma.it
GPG public key ID: FF5F32A8