From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx2.redhat.com (mx2.redhat.com [10.255.15.25]) by int-mx2.corp.redhat.com (8.13.1/8.13.1) with ESMTP id l1KH3xRC027150 for ; Tue, 20 Feb 2007 12:03:59 -0500 Received: from wr-out-0506.google.com (wr-out-0506.google.com [64.233.184.232]) by mx2.redhat.com (8.13.1/8.13.1) with ESMTP id l1KH3vxv021572 for ; Tue, 20 Feb 2007 12:03:57 -0500 Received: by wr-out-0506.google.com with SMTP id i23so2073283wra for ; Tue, 20 Feb 2007 09:03:57 -0800 (PST) Message-ID: <859a78260702200903o14188cb1hf874d589c5204698@mail.gmail.com> Date: Tue, 20 Feb 2007 11:03:56 -0600 From: "Matt P" Subject: Re: [linux-lvm] Re: LVM + Multipathing In-Reply-To: <20070220131909.GA26642@percy.comedia.it> MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <3nmja4-jtv.ln1@www.researchut.com> <20070220061150.GA3215@percy.comedia.it> <186ra4-8hp.ln1@www.researchut.com> <20070220131909.GA26642@percy.comedia.it> 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: linux-lvm@redhat.com Your problem might be related to this bug https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=213921 On 2/20/07, Luca Berra wrote: > On Tue, Feb 20, 2007 at 06:00:25PM +0530, Ritesh Raj Sarraf wrote: > >Luca Berra wrote: > > > >> On Sat, Feb 17, 2007 at 09:52:27PM +0530, Ritesh Raj Sarraf wrote: > >>>Hi, > >>> > >>>I have a question regarding the combination of LVM + Multipathing in a SAN > >>>environment. > >>> > >>>I have a LUN mapped to a host using iSCSI. I have two two paths to the LUN. > >>>This setup, using multipathing, provides me failover functionality. > >>> > >>>My question is how does LVM react to path failures ? > >>>In a failover environment, multipathing can take upto 120 seconds to detect > >>>that the active path to the LUN is no more available and then switch to the > >>>secondary path. During this 120 seconds, how does LVM react ? Does it really > >>>sense that the device is offlined ? Or that information is never passed to LVM > >>>and it just allows I/O to happen leaving that responsibility to the > >>>multipathing layer ? > >> > >> i believe LVM does not react at all. > >> > > > >I brought this question because I'm seeing Filesystem READONLY issues when doing > >a takeover/giveback. > > > >My understanding is that a filesystem usually goes read-only, only when it > >senses errors in the drive. Now I believe LVM might the culprit because beneath > >the filesystem and above the block device, LVM is the only layer. > to clarify my point above: > i meant that LVM (actually device-mapper) does not do anything special. > it just passes the IO requests from the fs layer to the > underlying block device and if the underlyng block device returns an IO > error then it is passed back to the fs. which will cause ext2 to remount > the filesystem readonly. > > L. > > -- > Luca Berra -- bluca@comedia.it > Communication Media & Services S.r.l. > /"\ > \ / ASCII RIBBON CAMPAIGN > X AGAINST HTML MAIL > / \ > > _______________________________________________ > linux-lvm mailing list > linux-lvm@redhat.com > https://www.redhat.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ >