[Imap-uw] Mix filesize

[Bob Atkins]

With files < 10MB in size what happens when an individual message is 
 >10MB? Does it span multiple files?

My basic concern was that the files size be an easily settable parameter 
so that we can each independently adjust it to suite our system's 
capabilities and performance. I would certainly hope and expect that the 
file size and mailbox format would automagically be handled correctly by 
the c-client library.

Mark Crispin wrote:
> On Fri, 14 Sep 2007, Per Foreby wrote:
>> I have changed MIXDATAROLL in src/osdep/unix/mix.c, and was a bit 
>> surprised when I used mixcvt and got the default filesize.
>> If this definition was moved to a common include file, say 
>> c-client/mix.h, all mix applications could share the same setting.
>
> mixcvt intentionally does not use any c-client information for mix; 
> the standalone mix tools follow their own rules and not c-client 
> rules.  Note that mixdfix and mixrbld don't even link with c-client at 
> all, and the only reason for mixcvt to link with c-client is to read 
> non-mix mailboxes.
>
> If you think about tweaking things, you'd see why you'd want mixcvt to 
> have its own independent idea.  But perhaps it should be a command 
> line option.
>
>> Has anyone made a serious attempt to see how large the files can be 
>> before they start to affect backup performance, or is everybody 
>> guessing?
>
> For the most part, everybody is guessing, but there seems to be some 
> concensus that a "good" value is between 1MB and 10MB for an "old" 
> data file.  That is likely to change over time as the average message 
> size grows.  The idea is to have an approximately two order of 
> magnitude reduction of number of files over maildir, news, mh, Cyrus, 
> etc.; while keeping the occasional expunge in an "old" file to 
> something manageable.
>
> I think though that we're all groping in the dark.  I agree that we 
> probably don't want it to be less than 1MB, so any tweaks to the 
> number will be to make it larger.  However, 500MB is probably way too 
> large.
>
> I'll be interested to hear how Nancy Lin does with 20MB.  I'd think 
> that "most of the .mix files get touched every day" would indicate 
> that the size is too large, and needs to be scaled back.
>
> But the only way is to play with lots of values in a real user and 
> production setting, and collect enough data that you can graph the 
> various values.  Sheesh, this is almost like multivariate calculus (a 
> class I still have nightmares about over 30 years later...).
>
> -- Mark --
>
> http://panda.com/mrc
> Democracy is two wolves and a sheep deciding what to eat for lunch.
> Liberty is a well-armed sheep contesting the vote.
> _______________________________________________
> Imap-uw mailing list
> Imap-uw at u.washington.edu
> https://mailman1.u.washington.edu/mailman/listinfo/imap-uw

-- 
*Bob Atkins * 
/President/CEO/

*DigiLink, Inc. <http://www.digilink.net>*
Business Inter-net-working
*/The Cure for the Common ISP!/*

	

Phone: (310) 577-9450
Fax: (310) 577-3360
eMail: bob at digilink.net

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman1.u.washington.edu/pipermail/imap-uw/attachments/20070913/d72b57a6/attachment-0001.htm
-------------- next part --------------
A non-text attachment was scrubbed...
Name: DigiLink_esig_logo.jpg
Type: image/jpeg
Size: 23605 bytes
Desc: not available
Url : http://mailman1.u.washington.edu/pipermail/imap-uw/attachments/20070913/d72b57a6/DigiLink_esig_logo-0001.jpg
-------------- next part --------------
A non-text attachment was scrubbed...
Name: bob.vcf
Type: text/x-vcard
Size: 279 bytes
Desc: not available
Url : http://mailman1.u.washington.edu/pipermail/imap-uw/attachments/20070913/d72b57a6/bob-0001.vcf