From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.redhat.com (mx1.redhat.com [172.16.48.31]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id n2GLrjGh012615 for ; Mon, 16 Mar 2009 17:53:45 -0400 Received: from mailmx.futuresource.com (mailmx.futuresource.com [208.10.26.74]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id n2GLrV81016306 for ; Mon, 16 Mar 2009 17:53:31 -0400 Received: from ns1.futuresource.com ([10.207.192.126]) by mailmx.futuresource.com (8.13.8/8.13.8) with ESMTP id n2GLrUro015888 for ; Mon, 16 Mar 2009 16:53:31 -0500 Received: from [10.207.193.131] (les-xp.futuresource.com [10.207.193.131]) by ns1.futuresource.com (8.11.6/8.11.6) with ESMTP id n2GLrUr17447 for ; Mon, 16 Mar 2009 16:53:30 -0500 Message-ID: <49BECA5A.3040407@gmail.com> Date: Mon, 16 Mar 2009 16:53:30 -0500 From: Les Mikesell MIME-Version: 1.0 Subject: Re: [linux-lvm] fsync() and LVM References: <49BA9BF9.3070507@esiway.net> <7B7881568CF40E4388B615CD06F87B98098BDA@clara.maurer-it.com> <49BC511E.5040402@esiway.net> <49BE9F73.8050109@gmail.com> <87f94c370903161236y197edd7ehef3dc8eefc6d617b@mail.gmail.com> <49BEB683.7020209@gmail.com> <87f94c370903161354v2e43f13ci914f45175ca6af6f@mail.gmail.com> <49BEC1CC.5050900@gmail.com> <87f94c370903161436y40eddb3pe162bfa64a90e371@mail.gmail.com> In-Reply-To: <87f94c370903161436y40eddb3pe162bfa64a90e371@mail.gmail.com> 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"; format="flowed" To: LVM general discussion and development Greg Freemyer wrote: >>> I haven't seen anyone claim yet that there is support for fsync(), which >> must return the status of the completion of the operation to the >> application. If it does, then the discussion could turn to performance. >> > Is your specific interest to ext3? No, it is whether a useful fsync() is possible over LVM. > If so, I suggest you post a > question there along the lines of: > > Device Mapper does not support barriers if more than one physical > device is in use by the LV. If I'm using ext3 on a LV and I call > fsync() from user space, how is fsync() implemented. Or is it not? The point of fsync() is for an application to know that a write has been safely committed, as for example sendmail would do before acknowledging to the sender that a message has been accepted. The question isn't whether an application can call fsync() but rather whether it's return status is lying, making the underlying storage unsuitable for anything that needs reliability. -- Les Mikesell lesmikesell@gmail.com