From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christophe Varoqui Subject: Re: Technical information requested on MultiPath module of Linux Date: Sun, 09 Apr 2006 22:09:55 +0200 Message-ID: <44396A13.5010204@free.fr> References: Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Joanne Neil Cc: dm-devel@redhat.com List-Id: dm-devel.ids Joanne Neil a =E9crit : > Hello, > > I was in search of technical details on MultiPath module of Linux= . I found > the excellent page of christophe. I apologize for sending the email to= you > directly. Can I know: > > a. Which will be the right email forum to send technical/development qu= estions > on MultiPath for Linux? > > =20 dm-devel@redhat.com > b. I was looking at Linux 2.6.11 MultiPath code and found EMC CX/AX > specific code. This is where I am most interested in. Does it require t= hat > a storage vendor has to implement specific hooks for the generic MultiP= ath > code to work with their product in Linux?. If yes, can I be pointed lin= k or > references or document on what a storage vendor has to implement to > have their storage work on Linux. > > =20 I guess you refer to "hardware handlers" modules. Those are needed only=20 if special host-initiated action is needed for the storage hardware to=20 activate failback paths. This is often the case with asymmetric arrays. > c. From what I have read, the MultiPath architecture has changed from > Linux 2.4 and Linux 2.6. Is this correct?. And the device mapper archit= ecture > was introduced in Linux 2.6. > > =20 The DM multipath driver is lk2.6 only. The MD multipath driver was=20 available in lk2.4, and is still maintained in lk2.6. The=20 multipath-tools interface the DM framework only. > d. Will Linux 2.6 MultiPath code be applicable to Linux 2.4? > > =20 There is no plan for userspace tools to support lk2.4 (pre-sysfs=20 kernels, pre-kevents). Hardware handlers use a "lk2.6 DM" specific API. > Appreciate any help > > Regards > Joanne > =20