[Dovecot] linux 2.4 vs 2.6 kernel

[Paul Vatta]

>
>
>> ------------------------------------------------------------------------
>
We were posed with the same dilemma, but it was due to the need to stick 
with RHEL supplied packages (ReiserFS does not come with RHEL) that we 
stayed with ext3.
Our old production mail server, running our in-house flavour of Linux, 
was based on the 2.4 kernel with ReiserFS.

We load tested Dovecot with maildir under RHEL3 (2.4 kernel) using ext3 
and found it was unable to standup to our requirements.  In part this 
was due to an inordinate imap-login / pop-login processes being created 
and hanging around under RHEL3.
Using RHEL4 (2.6 kernel), we found we were able to handle the required 
load - this is the configuration we went live with.  Processes ended 
cleanly too (result of the improved schedular and how it interacted with 
our IBM x445 and its NUMA architecture?) and the I/O issues seemed to 
have been resolved - ext3 was fine.


>> Subject:
>> Re: [Dovecot] linux 2.4 vs 2.6 kernel
>> From:
>> Marc Perkel <marc at perkel.com>
>> Date:
>> Mon, 18 Jul 2005 18:33:54 -0700
>>
>> CC:
>> dovecot at dovecot.org
>>
>>
>>
>>
>> Curtis Maloney wrote:
>>
>>> Marc Perkel wrote:
>>>
>>>> Actually - yes. Same problem. But the solution is to use the Reiser 
>>>> Filesystem. It doesn't have the ext3 problem.
>>>
>>>
>>>
>>> Now, I don't want to start a religious war, but...
>>>
>>> Ext2 has the advantages that 1) it can fall back to ext2 in recovery 
>>> cases, and 2) because of that, it has all the well-tested ext2 
>>> recovery tools available.
>>>
>>> People I know who've used Reiser say it's wonderfuly fast, but if it 
>>> corrupts, well... save your time, and go straight to restoring your 
>>> backups.
>>>
>>> Also, take a look at the tune2fs options.  I understand -O dir_index 
>>> will set it to use a b-tree index for faster handling of large 
>>> directories.
>>>
>>> -- 
>>> Curtis Maloney
>>> cmaloney at cardgate.net
>>
>>
>> I've been using it for 5 years and it works great. It specifically 
>> eliminates the speed problems of Maildir where you have thousands of 
>> files in a single directory.  And it has infinite inodes so you never 
>> run out of them. Reiser is ideal for email systems.
>>
>>------------------------------------------------------------------------
>>
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