[Dovecot] Questions regarding dbox migration

[Mikkel]

Timo Sirainen skrev:
> On Wed, 2009-10-14 at 23:04 +0200, Mikkel wrote:
>> So basically you prefer mdbox but are maintaining dbox because of its 
>> almost lockless design which is better for NFS users?
>>
>> Do you consider it to be viable having two different dbox formats or are 
>> you planning to keep only one of them in a long term perspective?
> 
> I'm planning on keeping both of them. And it's not necessarily only
> because of NFS users. Multi-dbox was done mainly because filesystems
> suck (mailbox gets fragmented all around the disk). Maybe if filesystems
> in future suck less, single-dbox will be better. Or perhaps SSDs make
> the fragmentation problem mostly irrelevant.
> 

You are talking about directories being fragmented right?
In case of mdbox wouldn't you have the very same problem since larger 
files may be fragmented all over the disk just like many small files in 
a directory might?

> And note that there are no real world statistics on how much faster
> multi-dbox is compared to single-dbox (or maildir). Maybe the difference
> isn't all that big after all. Or maybe it's a lot bigger than I thought.
> I've no idea.

I think the impact on imap operations and mail delivery probably would 
very little due to bigger files.

But pop3 users just download everything once in a while and should 
benefit tremendously from just having to read one file sequentially as 
opposed to read many small files.



So I can definitely see the point in mdbox but I better stay away from 
it, using NFS... :/

Regards, Mikkel