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[linux-lvm] Re: Device-mapper submission for 2.4
- From: "Yanick Quirion" <yanick quirion neokimia com>
- To: <linux-lvm sistina com>
- Subject: [linux-lvm] Re: Device-mapper submission for 2.4
- Date: Thu Dec 11 14:53:02 2003
Is there a patch for device-mapper for kernel 2.4.23?
> -----Original Message-----
> From: Alasdair G Kergon [mailto:agk uk sistina com]
> Sent: 11 December, 2003 14:48
> To: linux-kernel vger kernel org; linux-lvm sistina com
> Cc: Paul Jakma; Mike Fedyk; Joe Thornber; Marcelo Tosatti; Linus
> Subject: [linux-lvm] Re: Device-mapper submission for 2.4
> On Wed, Dec 10, 2003 at 03:40:07PM -0800, Mike Fedyk wrote:
> > On Wed, Dec 10, 2003 at 05:00:43PM +0000, Paul Jakma wrote:
> > > On Wed, 10 Dec 2003 venom sns it wrote:
> > > > DM is back compatible with LVM1, tested and runs well.
> > > What about the patches posted by Joe last (?) week which remove
> > > support from 2.6 DM?
> They remove support for the broken version 1 of the device-mapper
> ioctl interface. This is nothing to do with LVM1.
> > If this is what I was reading being discussed a few weeks ago, then
> > support for the LVM1 sysctls/ioctls has/will be removed, so you will
> have to
> > use the DM utilities instead of the old LVM1 utilities. LVM1
> > should still be supported.
> 2.6 does not support LVM1 ioctls.
> LVM2 userspace tools and EVMS both support LVM1 on-disk format using
> Here's a reference sheet to help clarify the terminology and explain
> what's happening.
> LVM1 = Userspace tools + kernel ioctls included in marcelo's 2.4 tree
> - LVM1 kernel ioctls are *not* included in or available for 2.6
> - LVM1 userspace tools do *not* work with 2.6 kernels
> dm = Kernel driver (GPL) for new volume managers to use.
> - Included in Linus's 2.6 kernels.
> - Available as a patch for 2.4 kernels from the Sistina website.
> - Knows *nothing* about volume manager's on-disk metadata layouts.
> - Userspace volume managers (e.g. EVMS and LVM2) communicate via a
> ioctl interface.
> - This ioctl interface is currently "version 4" and we regard it as
> stable. [Some enhancements are on the horizon, but nothing that
> breaks existing code/binaries.]
> - An old development version of this device-mapper ioctl interface
> as "version 1" has problems with it, is deprecated and should be
> removed from kernel trees ASAP.
> Always use "version 4" when building new kernels today.
> libdevmapper = Userspace shared library (LGPL) which wraps a volume
> application interface around the device-mapper ioctls
> - Can determine transparently whether the kernel device-mapper is
> "version 4" dm ioctl interface or the deprecated "version 1"
> and adapt itself accordingly. [configure --enable-compat]
> - Can only communicate with device-mapper: it cannot use LVM1
> - Designed primarily for use by LVM2 tools. [EVMS does not use it]
> - Some parts of the libdevmapper API are not yet stable and are
> to get changed.
> dmsetup = Userspace utility (GPL) which provides full command-line
> the libdevmapper API.
> - Designed for use by shell scripts and for testing and debugging.
> - Command line interface may be considered stable. New features may
> added, but we'll try not to break existing commands.
> LVM2 = New Logical Volume Manager command line tools (GPL) designed to
> be backward-compatible with LVM1 and offering new features and
> more flexibility, configurability and stability.
> - Supports existing LVM1 on-disk metadata.
> This means you do *not* have to make changes to your existing
> LVM1 volumes to switch between using LVM1 and LVM2.
> - Uses command lines similar to LVM1.
> - By default uses a new on-disk metadata format supporting more
> features than the original LVM1 version.
> - Communicates with the device-mapper kernel driver via
> Miscellaneous points:
> - LVM1 uses block major number 58: dm selects one or more major
> dynamically as required instead.
> - LVM1 uses character major number 109: dm selects a misc minor
> dynamically instead.
> - There's a (non-devfs) script for creating /dev/mapper/control at
> startup (or after dm module load).
> - You can use LVM1 tools with unpatched 2.4 kernels.
> - You can use LVM2 tools with patched 2.4 and unpatched 2.6 kernels.
> - Device-mapper support for snapshots and pvmove is so far released
> only for 2.4. Patches for 2.6 are being tested.
> - Multipath and mirror support are under development for 2.6.
> (Then get back-ported to 2.4.)
> Web download page: http://www.sistina.com/products_lvm_download.htm
> The device-mapper tarball contains:
> device-mapper kernel patches - needed only for 2.4;
> userspace libdevmapper and dmsetup - needed with all dm kernels.
> The LVM2 tarball contains the LVM2 command line tools.
> Development code can be found via:
> http://people.sistina.com/~thornber/ (for kernel patches)
> http://www.sistina.com/products_CVS.htm (for userspace code)
> Device-mapper mailing list:
> agk uk sistina com
> linux-lvm mailing list
> linux-lvm sistina com
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
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