journaling fs and large mailbox format

[Eric Anderson]

Alin-Adrian Anton wrote:
> Dear Hackers,
> 
>     First of all thank you for your time and attention.
> 
>     I am in the position to implement a large-scale mail server and I 
> will never go for anything else but FreeBSD (fixation?).
> 
>     It should be able to handle graceously 4000 e-mail accounts where a 
> minimum of 50 Mb/mailbox would be a requirement. In the begining, it is 
> desirable that users could use as much free space as available, so this 
> implies some gigabytes/mailbox.
> 
>     I don't know if the mbox format can handle this, and I know Maildir 
> cannot handle this on UFS2 standard install, no matter of soft-updates. 
> (because it exhaustes the free nodes) So I currently have no solution 
> for this stuff.

I'm not sure how you came to this conclusion, or what the history is, 
but I see no reason why UFS2 would have any adverse affects on maildir 
format mail system.  You can set the number of inodes to be created to a 
higher number when using newfs on the filesystem, so if you believe that 
is an issue, you should be able to tweak it to your needs.  mbox starts 
to break down on large mailboxes with many messages.  50mb may or may 
not be in that range, but maildir is much better for performance.


>     I was wondering what is the status of Journaling File Systems on
> FreeBSD? Any which is usable and mature, with write access? XFS would 
> fit amazingly well with Maildir, but.. I doubt it's anything else but 
> readonly.

Not sure how journaling would help you much here, except for meta-data 
consistancy, which soft-updates gives you, and fsck times.

>     So any suggestion would really help a lot. Thank's in advance.

A quick note - run the mail area on a RAID array, preferrably a RAID0+1 
(or 10 depending on who you ask).  Disks are nearly always a bottleneck, 
so if you can keep your random read/writes fast, the whole system will 
feel snappy.

You might try posting this to freebsd-isp@, since many people there have 
much larger installations running than this, and can probably provide 
some good hints.


Eric


-- 
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Eric Anderson        Sr. Systems Administrator        Centaur Technology
Anything that works is better than anything that doesn't.
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