From: Alin-Adrian Anton (aantonspintech.ro)
Date: Wed Oct 05 2005 - 13:03:33 CDT

• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

Wietse Venema wrote:
>>>Alin-Adrian Anton:
>>>
>>>
>>>>Maildir creates many files and this brings problems on filesystems which
>>>>were not designed for journaling.
>>>
>>>
>>Wietse Venema wrote:
>>
>>>What is the basis for this statement?
>>>
>>>Have you heard of 4.4BSD soft updates? An UFS2 file system is as
>>>fast as a fully asynchronous file system, without the corruption.
>
>
> Alin-Adrian Anton:
>
>>Yes I heard of 4.4BSD soft updates....
>>
>>With all the respect, I just experienced it some time ago. And it does
>>creates lots of troubles, unless the filesystem is tuned for handling
>>the Maildirs. (less then 1000 accounts with "Leave messages on server
>>unless 7 days old" in Outlook did the job)
>
>
> That does not jive with the article you reference below, which has
> 9000 maildir users with 1 million messages total.
>
>
>>This means estimating the average size of the Maildir/ files, estimating
>>the total number of Maildirs (which is easier), and applying some math.
>>
>>I received a link which thoroughly explains the steps here:
>>http://www.mostlygeek.com/node/11
>
>
> That article is about choosing an optimal file system block size
> for 9000 maildir users with 1 million messages total. It finds that
> the UFS2 defaults are just fine.
>
> If you're concerned about maildir performance, journaling is a red
> herring. Journaling helps with crash recovery, and may speed up
> some write operations; it does not speed up read performance of
> lots of maildir files.
>
> You may be better off with RAID and large battery backed
> write cache.
>
> Wietse
>
>

That article is very valid (in the sense of a "recipe") for ANY number
of Maildirs and size of files, the very same instructions were given on
another list by freebsd experts.

And no, the default settings for FreeBSD will NOT work fine with the
enviroment of Maildirs I described. You may be speaking on suppositions,
I am speaking what I have seen with my own eyes twice, so it's
reproductible.

And yes, JFS just helps the recovery problems, no more lost+found dirs,
and so on. However it's an adjacent thing that most of the JFS work well
with Maildir (are able to handle a huge amount of files and directories
without considerably degrading performance, see XFS for example).

With respect,
--
Alin-Adrian Anton
GPG keyID 0x183087BA (B129 E8F4 7B34 15A9 0785 2F7C 5823 ABA0 1830 87BA)
gpg --keyserver pgp.mit.edu --recv-keys 0x183087BA

"It is dangerous to be right when the government is wrong." - Voltaire

• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]