[linux-lvm] Mirroring

[linux-lvm] Mirroring

[Chris Anderson]

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I have looked through the doc and I see that LVM stripes but how do you
setup a true mirror?  One hard dive mirrored to another hard drive (1 to
1).

Thanks,

   Chris Anderson

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Re: [linux-lvm] Mirroring

[Harald Milz]

Chris Anderson <chris@alwan.com> wrote:
> I have looked through the doc and I see that LVM stripes but how do you
> setup a true mirror?  One hard dive mirrored to another hard drive (1 to
> 1).

It's more like one partition or logical volume mirrored against another
one (not necessarily disks - you seem to be familiar with Novell). LVM
can't do this. Use MD.

-- 
If you sit down at a poker game and don't see a sucker, get up.  You're
the sucker.

Re: [linux-lvm] Mirroring

[Chris Anderson]

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Harald Milz wrote:

> Chris Anderson <chris@alwan.com> wrote:
> > I have looked through the doc and I see that LVM stripes but how do you
> > setup a true mirror?  One hard dive mirrored to another hard drive (1 to
> > 1).
>
> It's more like one partition or logical volume mirrored against another
> one (not necessarily disks - you seem to be familiar with Novell). LVM
> can't do this. Use MD.

I know veritas.  It has a SubDisk, Plex Volume setup.  A subdisk is part of a
disk and one or more subdisk make a Plex and one or more plexes make a
volume.  And a volume can be used as a mount point or whatever.

So if a disk goes bad only plexes with use a subdisk from that disk are
down.  And if a volume has two plex only one need to be up to run.  Later the
plex can be re-joined back to the volume and the data is synched back to the
other plex.

In a nut shell what happens when one disk goes down with LVM?  Can it be
setup to keep the volume up and alive and run and if so what is the best way?

>
>
> --
> If you sit down at a poker game and don't see a sucker, get up.  You're
> the sucker.

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Re: [linux-lvm] Mirroring

[A James Lewis]

What you're asking is can LVM be used in conjunction with MD, and is this
the correct solution or is LVM/MD going to merge or LVM duplicate MD's
work??

I'd like those answers too!!!!


On Fri, 11 Feb 2000, Chris Anderson wrote:

> Harald Milz wrote:
> 
> > Chris Anderson <chris@alwan.com> wrote:
> > > I have looked through the doc and I see that LVM stripes but how do you
> > > setup a true mirror?  One hard dive mirrored to another hard drive (1 to
> > > 1).
> >
> > It's more like one partition or logical volume mirrored against another
> > one (not necessarily disks - you seem to be familiar with Novell). LVM
> > can't do this. Use MD.
> 
> I know veritas.  It has a SubDisk, Plex Volume setup.  A subdisk is part of a
> disk and one or more subdisk make a Plex and one or more plexes make a
> volume.  And a volume can be used as a mount point or whatever.
> 
> So if a disk goes bad only plexes with use a subdisk from that disk are
> down.  And if a volume has two plex only one need to be up to run.  Later the
> plex can be re-joined back to the volume and the data is synched back to the
> other plex.
> 
> In a nut shell what happens when one disk goes down with LVM?  Can it be
> setup to keep the volume up and alive and run and if so what is the best way?
> 
> >
> >
> > --
> > If you sit down at a poker game and don't see a sucker, get up.  You're
> > the sucker.
> 

Re: [linux-lvm] Mirroring

[Chris Anderson]

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A James Lewis wrote:

> What you're asking is can LVM be used in conjunction with MD, and is this
> the correct solution or is LVM/MD going to merge or LVM duplicate MD's
> work??

What is MD and where can I get it?  And why would we not want LVM to do this?
That is what a logical volumne manager is for? Yes?

Please note that it a month veritas will be out for linux.  It will have these
options, I think maybe we should think about what options they have and maybe make
some plans for lvm.  I say "we" because I would love to help were I could.

>
>
> I'd like those answers too!!!!
>
> On Fri, 11 Feb 2000, Chris Anderson wrote:
>
> > Harald Milz wrote:
> >
> > > Chris Anderson <chris@alwan.com> wrote:
> > > > I have looked through the doc and I see that LVM stripes but how do you
> > > > setup a true mirror?  One hard dive mirrored to another hard drive (1 to
> > > > 1).
> > >
> > > It's more like one partition or logical volume mirrored against another
> > > one (not necessarily disks - you seem to be familiar with Novell). LVM
> > > can't do this. Use MD.
> >
> > I know veritas.  It has a SubDisk, Plex Volume setup.  A subdisk is part of a
> > disk and one or more subdisk make a Plex and one or more plexes make a
> > volume.  And a volume can be used as a mount point or whatever.
> >
> > So if a disk goes bad only plexes with use a subdisk from that disk are
> > down.  And if a volume has two plex only one need to be up to run.  Later the
> > plex can be re-joined back to the volume and the data is synched back to the
> > other plex.
> >
> > In a nut shell what happens when one disk goes down with LVM?  Can it be
> > setup to keep the volume up and alive and run and if so what is the best way?
> >
> > >
> > >
> > > --
> > > If you sit down at a poker game and don't see a sucker, get up.  You're
> > > the sucker.
> >

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Re: [linux-lvm] Mirroring

[Chris McKinley]

Hi, I am relatively new to this list, and to Linux LVM, but when Heinz was
at the U of MN last month, I asked this very question, and Heinz's
response was that there are not currently plans for mirroring LEs to PEs
precisely because this functionality is provided by md or RAID hardware.

MD is the kernel RAID facility, and provides mirroring (RAID 1) in kernel
software.  It provides several other RAID versions as well.

Heinz, habe ich es richtig verstanden?

-Chris McKinley

On Fri, 11 Feb 2000, A James Lewis wrote:

> 
> What you're asking is can LVM be used in conjunction with MD, and is this
> the correct solution or is LVM/MD going to merge or LVM duplicate MD's
> work??
> 
> I'd like those answers too!!!!
> 
> 
> On Fri, 11 Feb 2000, Chris Anderson wrote:
> 
> > Harald Milz wrote:
> > 
> > > Chris Anderson <chris@alwan.com> wrote:
> > > > I have looked through the doc and I see that LVM stripes but how do you
> > > > setup a true mirror?  One hard dive mirrored to another hard drive (1 to
> > > > 1).
> > >
> > > It's more like one partition or logical volume mirrored against another
> > > one (not necessarily disks - you seem to be familiar with Novell). LVM
> > > can't do this. Use MD.
> > 
> > I know veritas.  It has a SubDisk, Plex Volume setup.  A subdisk is part of a
> > disk and one or more subdisk make a Plex and one or more plexes make a
> > volume.  And a volume can be used as a mount point or whatever.
> > 
> > So if a disk goes bad only plexes with use a subdisk from that disk are
> > down.  And if a volume has two plex only one need to be up to run.  Later the
> > plex can be re-joined back to the volume and the data is synched back to the
> > other plex.
> > 
> > In a nut shell what happens when one disk goes down with LVM?  Can it be
> > setup to keep the volume up and alive and run and if so what is the best way?
> > 
> > >
> > >
> > > --
> > > If you sit down at a poker game and don't see a sucker, get up.  You're
> > > the sucker.
> > 
> 
> 

Re: [linux-lvm] Mirroring

[Heinz Mauelshagen]

> Hi, I am relatively new to this list, and to Linux LVM, but when Heinz was
> at the U of MN last month, I asked this very question, and Heinz's
> response was that there are not currently plans for mirroring LEs to PEs
> precisely because this functionality is provided by md or RAID hardware.

Yes.
The LVM covers the dynamic allocation of storage.
Either RAID soft- or hardware covers the redundancy.

IMO you get a much simpler systemarchitecture this way which is much
more reliable for day to day production.

IOW: it saves your money.

> 
> MD is the kernel RAID facility, and provides mirroring (RAID 1) in kernel
> software.  It provides several other RAID versions as well.

Exactly. RAID4+5 are the other ones.

> 
> Heinz, habe ich es richtig verstanden?

Ja 8)

Heinz

> 
> -Chris McKinley
> 
> On Fri, 11 Feb 2000, A James Lewis wrote:
> 
> > 
> > What you're asking is can LVM be used in conjunction with MD, and is this
> > the correct solution or is LVM/MD going to merge or LVM duplicate MD's
> > work??
> > 
> > I'd like those answers too!!!!

No merge activities so far.

> > 
> > 
> > On Fri, 11 Feb 2000, Chris Anderson wrote:
> > 
> > > Harald Milz wrote:
> > > 
> > > > Chris Anderson <chris@alwan.com> wrote:
> > > > > I have looked through the doc and I see that LVM stripes but how do you
> > > > > setup a true mirror?  One hard dive mirrored to another hard drive (1 to
> > > > > 1).
> > > >
> > > > It's more like one partition or logical volume mirrored against another
> > > > one (not necessarily disks - you seem to be familiar with Novell). LVM
> > > > can't do this. Use MD.
> > > 
> > > I know veritas.  It has a SubDisk, Plex Volume setup.  A subdisk is part of a
> > > disk and one or more subdisk make a Plex and one or more plexes make a
> > > volume.  And a volume can be used as a mount point or whatever.
> > > 
> > > So if a disk goes bad only plexes with use a subdisk from that disk are
> > > down.  And if a volume has two plex only one need to be up to run.  Later the
> > > plex can be re-joined back to the volume and the data is synched back to the
> > > other plex.
> > > 
> > > In a nut shell what happens when one disk goes down with LVM?  Can it be
> > > setup to keep the volume up and alive and run and if so what is the best way?
> > > 
> > > >
> > > >
> > > > --
> > > > If you sit down at a poker game and don't see a sucker, get up.  You're
> > > > the sucker.
> > > 
> > 
> > 
> 


-- 

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

Systemmanagement CS-TS                           T-Nova
                                                 Entwicklungszentrum Darmstadt
Heinz Mauelshagen                                Otto-Roehm-Strasse 71c
Senior Systems Engineer                          Postfach 10 05 41
                                                 64205 Darmstadt
mge@EZ-Darmstadt.Telekom.de                      Germany
                                                 +49 6151 886-425
                                                          FAX-386
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Re: [linux-lvm] Mirroring

[Brian Kress]

A James Lewis wrote:
> 
> What you're asking is can LVM be used in conjunction with MD, and is this
> the correct solution or is LVM/MD going to merge or LVM duplicate MD's
> work??

	Yes.  LVM on MD works great.  I have a 4 disk
RAID 5 that I run LVM on to chop up into more managable
chunks.  40GB for a single FS is a bit excessive.  I
do this with the new raid 0.90.  I've never tried
it with the kernel standard raid, but I think I've
seem success reports.
	Applying the LVM patch and the raid0.90 patch
gets you some errors in ll_rw_block.c, but if you know
C, you can pretty much figure out how to patch it by
hand.  If anyone wants to do this and needs help with
the patches, I'd be happy to help.
	LVM on top of MD is great.  I get redundancy
and managability.


Brian

Re: [linux-lvm] Mirroring

[Luca Berra]

On Fri, Feb 11, 2000 at 12:16:21PM -0600, Chris Anderson wrote:
> What is MD and where can I get it?  And why would we not want LVM to do this?
> That is what a logical volumne manager is for? Yes?

uhm...
> X-Mailer: Mozilla 4.7 [en] (X11; I; Linux 2.2.14 i686)
look at http://www.redhat.com/~mingo/raid-2.2.14-B1 for the patch
and http://ostenfeld.dk/~jakob/Software-RAID.HOWTO for the docs

i believe raid is being merged in the very latest 2.3.x kernel

> Please note that it a month veritas will be out for linux.  It will have these

i never believed in schedules :)

L.

-- 
Luca Berra -- bluca@comedia.it
    Communication Media & Services S.r.l.

Re: [linux-lvm] Mirroring

[Mats Wichmann]

At 01:18 AM 02/12/2000 +0100, Heinz Mauelshagen wrote:
>> Hi, I am relatively new to this list, and to Linux LVM, but when Heinz was
>> at the U of MN last month, I asked this very question, and Heinz's
>> response was that there are not currently plans for mirroring LEs to PEs
>> precisely because this functionality is provided by md or RAID hardware.
>
>Yes.
>The LVM covers the dynamic allocation of storage.
>Either RAID soft- or hardware covers the redundancy.
>
>IMO you get a much simpler systemarchitecture this way which is much
>more reliable for day to day production.
>
>IOW: it saves your money.

perhaps...but it makes it impossible, if I've understood this
architecture, to use a floating mirror for live backups.

i.e., set up 3 10 gb partitions "a" "b" and "c", and one 10 gb spare "d"

attach "d" as a mirror of "a", wait for sync, detach, backup "d"
attach "d" as a mirror of "b", wait for sync, detach, backup "d"
etc.

(for redundant situations, "a" "b" and "c" may already be mirrored
so you're attaching the floater as an _additional_ mirror)

maybe the application for such usage is not widespread enough, though...

Re: [linux-lvm] Mirroring

[Michael Marxmeier]

> perhaps...but it makes it impossible, if I've understood this
> architecture, to use a floating mirror for live backups.
> 
> i.e., set up 3 10 gb partitions "a" "b" and "c", and one 10 gb spare "d"
> 
> attach "d" as a mirror of "a", wait for sync, detach, backup "d"
> attach "d" as a mirror of "b", wait for sync, detach, backup "d"
> etc.

AFAICS you can do the same with LVM snapshots (not fully working yet).
Either create an LVM snapshot and backup the snapshot directly or copy
the snapshot to an extra lvol.
IMHO you get the same result by using a different machanism.


Just a thought
Michael

--
Michael Marxmeier           Marxmeier Software AG
E-Mail: mike@msede.com      Besenbruchstrasse 9
Phone : +49 202 2431440     42285 Wuppertal, Germany
Fax   : +49 202 2431420     http://www.msede.com/

Re: [linux-lvm] mirroring

[Harik A'ttar]

Harik A'ttar wrote:

> You've merged the 2.6.16.16 patch with the mirroring patch.   Can you 
> redo the patch from the same versions?

Duh, I just used zcat | less to read it, completely ignoring the fact
it was a tarball.  It's already split out nicely, I'm just running slow 
today.

Re: [linux-lvm] mirroring

[Harik A'ttar]

Jens Wilke wrote:
> On Thursday 18 May 2006 10:05, Jonathan E Brassow wrote:
>> I think most of the device-mapper and LVM2 patches for mirroring have
>> been put into CVS.  device-mapper kernel patches for various kernels
>> can be found at https://www.brassow.com/mirroring.
> 
> It's working better without https ;)
> 
> http://www.brassow.com/mirroring

Wow, that's rather a mess.

diff --git a/Makefile b/Makefile
index cb57905..b93f75f 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
  VERSION = 2
  PATCHLEVEL = 6
  SUBLEVEL = 16
-EXTRAVERSION =
+EXTRAVERSION = .16
  NAME=Sliding Snow Leopard

  # *DOCUMENTATION*

You've merged the 2.6.16.16 patch with the mirroring patch.   Can you 
redo the patch from the same versions?

Re: [linux-lvm] mirroring

[Jens Wilke]

On Thursday 18 May 2006 10:05, Jonathan E Brassow wrote:
> I think most of the device-mapper and LVM2 patches for mirroring have
> been put into CVS.  device-mapper kernel patches for various kernels
> can be found at https://www.brassow.com/mirroring.

It's working better without https ;)

http://www.brassow.com/mirroring

Regards,

Jens

-- 
�Jens Wilke

� �// http://www.headissue.com - headissue GmbH - Munich - Germany
�\// �"Don't wait for something you have to do yourself"

[linux-lvm] mirroring

[Jonathan E Brassow]

I think most of the device-mapper and LVM2 patches for mirroring have 
been put into CVS.  device-mapper kernel patches for various kernels 
can be found at https://www.brassow.com/mirroring.

  brassow

Re: [linux-lvm] mirroring

[James Pattinson]

This reminds me of something - I used to use purely md on my system,
striping across SCSI and IDE disks for maximum performance. Using hdpart
-t, I got 25MB per second throughput on /dev/md0, now I'm using LVM on
it's own, but still striping using LVM, and I only seem to get about 17MB
per sec. I *much* prefer using a LVM'd system though, and this performance
doesn't really matter to me. 

I recall that the raid patches use MMX or something for higher performance
- is this something LVM could do as well, or do people recommend making a
big fast /dev/md0 then throwing it into a vg? of course then we have all
the raid0145+lvm patch issues... grrrr... how bad is the stock kernel raid
support anyway? :)

Well, cheers, and keep up the darn good work all you developers (Heinz
especially :) )

James

On Mon, 22 Nov 1999, Michael Marxmeier wrote:

> Hello Brian,
> 
> > 	Looking at this LVM for linux, it all seems very familiar to me 
> > as an HPUX administrator.  However, the one thing that I don't see is the
> > ability to do RAID1 (mirroring).  Is that available, or will it be in the
> > future?
> 
> You can use LVM on top of MD which provides RAID 1 and 5.
> It was initially planned to have RAID 1 in LVM but so far
> this has not been done.
> 
> It would be nice to have RAID and LVM more integrated (from the
> administrative point of view).
> 
> 
> Hope this helps
> Michael
> 
> --
> Michael Marxmeier           Marxmeier Software AG
> E-Mail: mike@msede.com      Besenbruchstrasse 9
> Phone : +49 202 2431440     42285 Wuppertal, Germany
> Fax   : +49 202 2431420     http://www.msede.com/
> 

Re: [linux-lvm] mirroring

[Michael Marxmeier]

Hello Brian,

> 	Looking at this LVM for linux, it all seems very familiar to me 
> as an HPUX administrator.  However, the one thing that I don't see is the
> ability to do RAID1 (mirroring).  Is that available, or will it be in the
> future?

You can use LVM on top of MD which provides RAID 1 and 5.
It was initially planned to have RAID 1 in LVM but so far
this has not been done.

It would be nice to have RAID and LVM more integrated (from the
administrative point of view).


Hope this helps
Michael

--
Michael Marxmeier           Marxmeier Software AG
E-Mail: mike@msede.com      Besenbruchstrasse 9
Phone : +49 202 2431440     42285 Wuppertal, Germany
Fax   : +49 202 2431420     http://www.msede.com/

[linux-lvm] mirroring

[Brian C. Huffman]

All,

	Looking at this LVM for linux, it all seems very familiar to me 
as an HPUX administrator.  However, the one thing that I don't see is the
ability to do RAID1 (mirroring).  Is that available, or will it be in the
future?

Brian

---

Brian C. Huffman
Associate Systems Engineer - Information Resources
DuPont Pharmaceuticals Company
Little Falls 1, Suite 215 / Room 205
2711 Centerville Road
Wilmington, DE 19808