[linux-lvm] [ANNOUNCE] LVM reimplementation ready for beta testing

[linux-lvm] [ANNOUNCE] LVM reimplementation ready for beta testing

[Joe Thornber]

All,

Sistina is pleased to announce that the LVM2 software is ready for
beta testing.

This is a complete reimplementation of the existing LVM system, both
driver and userland tools.

We encourage you to give it a try and feed back your test results,
bug-fixes, enhancement requests etc. through the normal lists
linux-lvm@sistina.com and lvm-devel@sistina.com.

The new kernel driver (known as "device-mapper") supports volume
management in general and is no longer Linux LVM specific.
As such it is a separate package from LVM2 which you will need
to download and install before building LVM2.

 ftp://ftp.sistina.com/pub/LVM2/device-mapper/device-mapper-beta1.tgz


The userland tools are available from here:

 ftp://ftp.sistina.com/pub/LVM2/tools/LVM2.0-beta1.tgz


This release does not support snapshots or pvmove.  These features
will go into a subsequent beta release, hopefully within the next
fortnight.

This is Beta software which is *not* meant to be running on your
production systems.  If necessary, keep backups of your data and LVM
metadata (/etc/lvmconf/*).


We look forward to your feedback.


The Sistina LVM team:

      Patrick Caulfield,
      Alasdair Kergon,
      Heinz Mauelshagen,
      Joe Thornber

[linux-lvm] Re: [lvm-devel] [ANNOUNCE] LVM reimplementation ready for beta testing

[Andreas Dilger]

On Jan 30, 2002  20:22 +0000, Joe Thornber wrote:
> Sistina is pleased to announce that the LVM2 software is ready for
> beta testing.
> 
> This is a complete reimplementation of the existing LVM system, both
> driver and userland tools.

What is the current and future licensing of the LVM2 code?  Given the
GFS events, I think people will be hesitant to accept an all-Sistina
reimplementation of LVM.

Cheers, Andreas
--
Andreas Dilger
http://sourceforge.net/projects/ext2resize/
http://www-mddsp.enel.ucalgary.ca/People/adilger/

[linux-lvm] Re: [lvm-devel] [ANNOUNCE] LVM reimplementation ready for beta testing

[Jim McDonald]

On Wed, 2002-01-30 at 21:54, Andreas Dilger wrote:
> On Jan 30, 2002  20:22 +0000, Joe Thornber wrote:
> > Sistina is pleased to announce that the LVM2 software is ready for
> > beta testing.
> > 
> > This is a complete reimplementation of the existing LVM system, both
> > driver and userland tools.
> 
> What is the current and future licensing of the LVM2 code?  Given the
> GFS events, I think people will be hesitant to accept an all-Sistina
> reimplementation of LVM.

Also, does/where does this fit in with EVMS?

Cheers,
Jim.
-- 
Jim McDonald - Jim@mcdee.net

Re: [linux-lvm] Re: [lvm-devel] [ANNOUNCE] LVM reimplementation ready for beta testing

[James Hawtin]

Licencing is important to me, too. Also is it pv/lv compatible with lvm 1
or is it system rebuild time.....

James

[linux-lvm] Re: [ANNOUNCE] LVM reimplementation ready for beta testing

[Lars Kellogg-Stedman]

> Also, does/where does this fit in with EVMS?

It doesn't :).  They're essentially competing implementations that offer 
similar functionality.  I've been running the EVMS stuff for a while 
now, and it's (a) been pretty darn solid, and (b) is completely 
compatible with LVM1 on disk.

The next release of EVMS should also allow you to replace the standard 
MD subsystem (RAID 0/1/5) with EVMS.

I think that, in general, competition is good.  A stable, robust, and 
flexible logical volume implementation is a good thing, and we'll 
probably get there faster with two groups acting as inspirations for 
each other.

Cheers,

-- Lars

[linux-lvm] Re: [ANNOUNCE] LVM reimplementation ready for beta testing

[Daniel Phillips]

On January 30, 2002 09:22 pm, Joe Thornber wrote:
> The new kernel driver (known as "device-mapper") supports volume
> management in general and is no longer Linux LVM specific.
> As such it is a separate package from LVM2 which you will need
> to download and install before building LVM2.
> 
>  ftp://ftp.sistina.com/pub/LVM2/device-mapper/device-mapper-beta1.tgz

Hi, thanks a lot for this fine gift.  One small point: I downloaded these
files right away of course, then I renamed device-mapper-beta1.tgz as
LVM2-mapper-beta1.tgz, so I'd be able to find these things in my (very
full) download directory.  What do you think about doing it that way at
source?

> The userland tools are available from here:
> 
>  ftp://ftp.sistina.com/pub/LVM2/tools/LVM2.0-beta1.tgz

-- 
Daniel

Re: [linux-lvm] Re: [lvm-devel] [ANNOUNCE] LVM reimplementation ready for beta testing

[Joe Thornber]

On Wed, Jan 30, 2002 at 10:03:40PM +0000, Jim McDonald wrote:
> Also, does/where does this fit in with EVMS?

EVMS differs from us in that they seem to be trying to move the whole
application into the kernel, whereas we've taken the opposite route
and stripped down the kernel side to just provide services.

This is fine, I think there's room for both projects.  But it is worth
noting that EVMS could be changed to use device-mapper for it's low
level functionality.  That way they could take advantage of the cool
work we're doing with snapshots and pvmove, and we could take
advantage of having more eyes on the core driver.

LVM2 may not seem that exciting initially, since the first release is
just concentrating on reproducing LVM1 functionality.  But a lot of
the reason for this rewrite is to enable us to add in the new features
that we want (such as a transaction based disk format).  It's on this
new feature list that we'll be mainly competing with EVMS.

- Joe

[linux-lvm] Re: [lvm-devel] [ANNOUNCE] LVM reimplementation ready for beta testing

[Joe Thornber]

On Wed, Jan 30, 2002 at 02:54:08PM -0700, Andreas Dilger wrote:
> On Jan 30, 2002  20:22 +0000, Joe Thornber wrote:
> > Sistina is pleased to announce that the LVM2 software is ready for
> > beta testing.
> > 
> > This is a complete reimplementation of the existing LVM system, both
> > driver and userland tools.
> 
> What is the current and future licensing of the LVM2 code?  Given the
> GFS events, I think people will be hesitant to accept an all-Sistina
> reimplementation of LVM.


LVM2 is GPL/LGPL-licensed - just like the original version of LVM.
This means the whole Linux community benefits from this aspect of
Sistina's work.  The device-mapper and LVM2 packages will *always* be
GPL/LGPL.

As those who have been following LVM development closely will be aware,
the decision to rewrite was taken for sound technical - not licensing -
reasons, and of course we welcome and encourage contributions to LVM2
from outside Sistina.

- Joe

Re: [linux-lvm] Re: [lvm-devel] [ANNOUNCE] LVM reimplementation ready for beta testing

[Heinz J . Mauelshagen]

On Wed, Jan 30, 2002 at 10:36:10PM +0000, James Hawtin wrote:
> Licencing is important to me, too. Also is it pv/lv compatible with lvm 1
> or is it system rebuild time.....

LVM2 supports the existing LVM1 on disk metadata format and will support another
so called format2 soon which has enhanced metadata redundancy and transaction 
oriented updates in order to largely reduce the likelyhood of inacessable
VGs and metadata restores.

IOW: it will make LVM more insensible to hardware flaws.


> 
> James
> 
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html

Regards,
Heinz    -- The LVM Guy --

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Heinz Mauelshagen                                 Sistina Software Inc.
Senior Consultant/Developer                       Am Sonnenhang 11
                                                  56242 Marienrachdorf
                                                  Germany
Mauelshagen@Sistina.com                           +49 2626 141200
                                                       FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Re: [linux-lvm] Re: [ANNOUNCE] LVM reimplementation ready for beta testing

[Heinz J . Mauelshagen]

On Thu, Jan 31, 2002 at 02:53:10AM +0100, Daniel Phillips wrote:
> On January 30, 2002 09:22 pm, Joe Thornber wrote:
> > The new kernel driver (known as "device-mapper") supports volume
> > management in general and is no longer Linux LVM specific.
> > As such it is a separate package from LVM2 which you will need
> > to download and install before building LVM2.
> > 
> >  ftp://ftp.sistina.com/pub/LVM2/device-mapper/device-mapper-beta1.tgz
> 
> Hi, thanks a lot for this fine gift.  One small point: I downloaded these
> files right away of course, then I renamed device-mapper-beta1.tgz as
> LVM2-mapper-beta1.tgz, so I'd be able to find these things in my (very
> full) download directory.  What do you think about doing it that way at
> source?

Well, as said in the annoucement the device-mapper is no longer Linux LVM
specific and therefore we choosed to give it a name without any 'LVM' substring
in its name. device-mapper is just a package LVM2 needs to run beside others
like linux-kernel ;-)

> 
> > The userland tools are available from here:
> > 
> >  ftp://ftp.sistina.com/pub/LVM2/tools/LVM2.0-beta1.tgz
> 
> -- 
> Daniel
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html

-- 

Regards,
Heinz    -- The LVM Guy --

*** Software bugs are stupid.
    Nevertheless it needs not so stupid people to solve them ***

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Heinz Mauelshagen                                 Sistina Software Inc.
Senior Consultant/Developer                       Am Sonnenhang 11
                                                  56242 Marienrachdorf
                                                  Germany
Mauelshagen@Sistina.com                           +49 2626 141200
                                                       FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

[linux-lvm] Re: [ANNOUNCE] LVM reimplementation ready for beta testing

[Arjan van de Ven]

On Thu, Jan 31, 2002 at 01:09:13PM +0000, Joe Thornber wrote:
> 
> Now our hero decides to PV move PV2 to PV4:
> 
> 1. Suspend our LV (254:3), this starts queueing all io, and flushes
>    all pending io. 

But "flushes all pending io" is *far* from trivial. there's no current
kernel functionality for this, so you'll have to do "weird shit" that will
break easy and often.

Also "suspending" is rather dangerous because it can deadlock the machine
(think about the VM needing to write back dirty data on this LV in order to
 make memory available for your move)...

Greetings,
  Arjan van de Ven

[linux-lvm] Re: [ANNOUNCE] LVM reimplementation ready for beta testing

[Joe Thornber]

On Fri, Feb 01, 2002 at 05:12:51AM -0500, Arjan van de Ven wrote:
> On Thu, Jan 31, 2002 at 01:09:13PM +0000, Joe Thornber wrote:
> > 
> > Now our hero decides to PV move PV2 to PV4:
> > 
> > 1. Suspend our LV (254:3), this starts queueing all io, and flushes
> >    all pending io. 
> 
> But "flushes all pending io" is *far* from trivial. there's no current
> kernel functionality for this, so you'll have to do "weird shit" that will
> break easy and often.

Here's the weird shit.  If you can see how to break it, I'd like to
know.

Whenever the dm driver maps a buffer_head, I increment a 'pending'
counter for that device, and hook the bh->b_end_io, bh->b_private
function so that this counter is decremented when the io completes.
This doesn't work with ext3 on 2.4 kernels since ext3 believes the
b_private pointer is for general filesystem use rather than just
b_end_io, however Stephen Tweedie and I have been discussing ways to
get round this.  On 2.5 this works fine since the bio->bi_private
isn't abused in this way.

> Also "suspending" is rather dangerous because it can deadlock the machine
> (think about the VM needing to write back dirty data on this LV in order to
>  make memory available for your move)...

You are correct, this is the main flaw IMO with the LVM1 version of
pvmove (which was userland with locking on a per extent basis).

However for LVM2 the device will only be suspended while a table
is loaded, *not* while the move takes place.  I will however allocate
the struct deferred_io objects from a mempool in 2.5.

- Joe

[linux-lvm] Re: [ANNOUNCE] LVM reimplementation ready for beta testing

[Alan Cox]

> But "flushes all pending io" is *far* from trivial. there's no current
> kernel functionality for this, so you'll have to do "weird shit" that will
> break easy and often.
> 
> Also "suspending" is rather dangerous because it can deadlock the machine
> (think about the VM needing to write back dirty data on this LV in order to
>  make memory available for your move)...

I don't think you need to suspend I/O except momentarily. I don't use LVM and
while I can't resize volumes I migrate them like this

	mdhotadd /dev/md1 /dev/newvolume

[wait for it to resync]

	mdhotremove /dev/md1 /dev/oldvolume

the situation here seems analogous. You never need to suspend I/O to the
volume until you actually kill it, by which time you can just skip the write
to the dead volume.

(The above procedure with ext3 does btw make a great backup system 8))

Alan