From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id n2GB2snG032143 for ; Mon, 16 Mar 2009 07:02:54 -0400 Received: from thb-mta-18.emailfiltering.com (thb-mta-18-tx.emailfiltering.com [194.116.199.213]) by mx3.redhat.com (8.13.8/8.13.8) with ESMTP id n2GB2d3q007535 for ; Mon, 16 Mar 2009 07:02:39 -0400 Received: from smtp.media-brokers.com ([70.43.81.99]) by thb-mta-18.emailfiltering.com with emfmta (version 3.7.1.44.1.r-3.2.3-libc2.3.2) vanilla id 1110840886 for linux-lvm@redhat.com; Mon, 16 Mar 2009 11:02:38 +0000 Received: from [192.168.1.110] (sjester.atl.media-brokers.com [192.168.1.110]) by smtp.media-brokers.com (Postfix) with ESMTPSA id 725C42D7F66 for ; Mon, 16 Mar 2009 07:02:37 -0400 (EDT) Message-ID: <49BE31CC.7050905@Media-Brokers.com> Date: Mon, 16 Mar 2009 07:02:36 -0400 From: Charles Marcus MIME-Version: 1.0 Subject: Re: [linux-lvm] fsync() and LVM References: <49BA9BF9.3070507@esiway.net> <20090313203812.GK7445@agk.fab.redhat.com> <7B7881568CF40E4388B615CD06F87B98098BDA@clara.maurer-it.com> <49BC511E.5040402@esiway.net> In-Reply-To: <49BC511E.5040402@esiway.net> Content-Transfer-Encoding: 7bit Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii" To: LVM general discussion and development On 3/14/2009 8:51 PM, Marco Colombo wrote: > Stuart D. Gathman wrote: >> On Sat, 14 Mar 2009, Dietmar Maurer wrote: >> It just means that write barriers won't get passed to the device. >> This is only a problem if the devices have write caches. Note >> that with multiple devices, even a FIFO write cache could cause >> reordering between devices (one device could finish faster than another). > No, it's more than that. PostgreSQL gurus say LVM doesn't honor fsync(), > that data doesn't even get to the controller, and it doesn't matter > if the disks have write caches enabled or not. Or if they have battery backed > caches. Please read the thread I linked. If what they say it's true, > you can't use LVM for anything that needs fsync(), including mail queues > (sendmail), mail storage (imapd), as such. So I'd really like to know. Seeing as my /var (with both postfix & courier-imap using it for mail storage) has been on lvm for almost 4 years, that would be news to me... ;) -- Best regards, Charles