linux-kernel - Re: Ext4 and the "30 second window of death"

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Date:	Fri, 3 Apr 2009 09:36:59 +1100
From:	Bron Gondwana <brong@...tmail.fm>
To:	david@...g.hm
Cc:	Matthew Garrett <mjg59@...f.ucam.org>,
	Theodore Tso <tytso@....edu>,
	Sitsofe Wheeler <sitsofe@...oo.com>,
	"Andreas T.Auer" <andreas.t.auer_lkml_73537@...us.ath.cx>,
	Alberto Gonzalez <info@...bu.es>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Ext4 and the "30 second window of death"

On Thu, Apr 02, 2009 at 11:44:20AM -0700, david@...g.hm wrote:
> let's not talk a database here, let's talk something simpler, like a POP3 
> mail client (even though I strongly favor IMAP ;-)
>
> it wants to have the message saved before it deletes it from the server.
>
> how should it try to do this?
>
> the only portable method is to fsync the file after it's written and  
> before sending the delete to the server.
>
> so your mail client _should_ issue fsync calls.
>
> however, some (many, most??) users would probably be willing to loose a  
> little e-mail to gain a significant increase in battery life on their  
> laptops.

Obviously it should do a spamminess test.  If the sender is in your
addressbook/whitelist then fsync it, otherwise if it looks spammy,
don't bother.

Seriously, there's no way of telling which emails are the really
important job offer/flight confirmation/invitation from that really
cute girl you met that one time...

... lots of data is like that.  It's usually not important except
when it really, really is - and the average user don't want to be
babysitting every single decision about importance.

  "Your email program wants to spin up the disk to store a message,
   confirm or deny"

Bron.
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