[Novalug] thinking about switching to maildir

[John Franklin]

On Apr 3, 2012, at 6:07 PM, Mark Smith wrote:
> On Tue, Apr 03, 2012 at 12:45:21PM -0400, The Doctor wrote:
>> I think you'll find Maildirs a bit faster (because the IMAP server
>> won't have to sequentially page through a huge file to find messages)
>> and more reliable (more eggs, more baskets).
> 
> i've heard that searches will be slower?


I'd love to see some performance numbers before and after the conversion.  The MBOX format is a single large file, but dovecot creates an index of the messages in it in a separate file so it's less read-read-read and more read-seek-read, or (perhaps better still) dovecot may mmap() the whole mbox file and use the index as offsets into the memory block.  The mmap() method puts stress on the memory manager to page in parts of the mbox as needed.

Now, deleting mail is going to be faster because there's no need to compact the mbox.  However, general reading may create more server load as each file requires its own lookup() and open() and thus a new vnode, putting much more stress on the VFS.

Searches... depends.  How does your client do the search and what is it searching?

jf
-- 
John Franklin
franklin at elfie.org
ICBM: 39º 01' 58.4"N 77º 24' 49.6"W Z+84m

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