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 n6QAD4RN016921 for ; Sun, 26 Jul 2009 06:13:04 -0400 Received: from ey-out-2122.google.com (ey-out-2122.google.com [74.125.78.24]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id n6QACoXG002312 for ; Sun, 26 Jul 2009 06:12:50 -0400 Received: by ey-out-2122.google.com with SMTP id 9so596814eyd.39 for ; Sun, 26 Jul 2009 03:12:49 -0700 (PDT) MIME-Version: 1.0 Date: Sun, 26 Jul 2009 12:12:49 +0200 Message-ID: <29ae894c0907260312m3b2ffb2ex5cbef456f3c49bee@mail.gmail.com> From: brem belguebli Content-Type: multipart/alternative; boundary=00504502c89e661a1e046f99147e Subject: [linux-lvm] Mirroring implementation 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: To: linux-lvm@redhat.com --00504502c89e661a1e046f99147e Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Hi, I have a few questions concerning LVM mirror implementation, and I couldn't find any suitable design doc I need to setup a dual site ( a few miles between the 2 sites, around 1 ms RTD) mirror based cluster system. - what is the default behaviour of the mirroring, writing in parallel to both mirror legs or serialized ? what about read requests ? - for write requests, is the ack returned to the application (thru VFS) when the 2 legs are updated or only when the first is updated ? - Is there a way to control it ? - what happens if the log device is lost ? I saw a post about LVM mirror vs mdadm where it is about the location of the mirror log ( https://www.redhat.com/archives/linux-lvm/2009-July/msg00012.html) someone gave the answer that when creating the LV's with --alloc anywhere it will auto locate the log on any of the PV's. According to what I could read, the --alloc doesn't intend for that, am I right ? Brem , --00504502c89e661a1e046f99147e Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Hi,

I have a few questions concerning LVM mirror impleme= ntation, and I couldn't find any suitable design doc

I need to setup a dual site ( a few miles between the 2 sites, aroun= d 1 ms RTD) mirror based cluster system.

- =A0what is the default behaviour of the mirroring, wr= iting in parallel to both mirror legs or serialized ? what about read reque= sts ?

- for write requests, is the ack returned to= the application (thru VFS) when the 2 legs are updated or only when the fi= rst is updated ?
- Is there a way to control it ?

- what happe= ns if the log device is lost ?

I saw a post about = LVM mirror vs mdadm where it is about the location of the m= irror log (https://www.redhat.com/archives/linux-lvm= /2009-July/msg00012.html) someone gave the answer that when creating th= e LV's with --alloc anywhere it will auto locate the log on any of the = PV's.

According to what = I could read, the --alloc doesn't intend for that, am I right ?<= /span>

Brem ,=A0=A0
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