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* [linux-lvm] RAID and LVM?
@ 1999-07-14 22:38 Paul Jakma
  1999-07-14 23:04 ` Heinz Mauelshagen
  0 siblings, 1 reply; 25+ messages in thread
From: Paul Jakma @ 1999-07-14 22:38 UTC (permalink / raw)
  To: Linux LVM list, Linux Raid Mailing List

I'm wondering: is it possible to run LVM on top of the linux-raid
patches?

I'd like to carve up my disks into 500MB RAID-5 devices, and then
build LVM on top of the /dev/md devices instead of the usual
/dev/sd{a1,b1.. etc} devices.

Should I try it? or do the 2 patches tread on each others toes? (i
notice they both touch buffer.c). 

if it can't be done, then are there any plans to integrate linux-raid
and linux-lvm, or change LVM to able to use md devices?

(LVM and RAID are very complementary... really should be merged)

thanks,
-- 
Paul Jakma
paul@clubi.ie	http://hibernia.clubi.ie
PGP5 key: http://www.clubi.ie/jakma/publickey.txt
-------------------------------------------
Fortune:
Don't get suckered in by the comments -- they can be terribly misleading.
Debug only code.
		-- Dave Storer

^ permalink raw reply	[flat|nested] 25+ messages in thread
* Re: [linux-lvm] RAID and LVM?
@ 1999-07-27 12:23 Heinz Mauelshagen
  1999-07-27 12:57 ` Luca Berra
  0 siblings, 1 reply; 25+ messages in thread
From: Heinz Mauelshagen @ 1999-07-27 12:23 UTC (permalink / raw)
  To: linux-lvm


> 
> On Mon, Jul 26, 1999 at 10:25:50PM +0200, Ingo Molnar wrote:
> > (rather flame me for it ;) The new RAID driver will likely not go into
> > 2.2.11, but into 2.2.12. Anyway, the new RAID 0723 release is much more
> > merging-friendly wrt. LVM.
> 
> ok, you asked for it ;)
> there is still some idiosyncrasye wrt HSM and it doesn't build.
> *joking*
> 2.2.11 or 2.2.12 does not seem to be a big problem to me.
> 
> > > or ideally for raid to be fully integrated into LVM, and create
> > > RAID-5 VG's. 
> > or, considering the relative complexity of the two drivers (and the
> > conceptual background), to integrate LVM into the concepts of RAID :) Or
> i dont understand your last sentence
> > let them live side by side as now.
> 
> i believe useful integrating raid and lvm
> it means a user can dcide the different raid policy
> for each type of data.
> eg. striping for /var/spool/junk
> 3 way raid1 for /very/important/stuff
> raid5 for /other/data

That's the Veritas Volume Manager concept.

> 
> Leaving things as now is still very useful, and i will be very 
> happy to have this arrangement finalized.
> we really need to fix LILO (or another boot loader, grub already
> can read ext2 filesystems) to be able to understand raid and lvm.
> 
> as a side question, how does LVM autodetect works
> (if it exists, that is)?
> 

Today, it's the initrd mechanism (partially) supported by lvmcreate_initrd
in LVM 0.7.
Basically the idea is to have a bios addressable partition (8MB is sufficient)
with initrd, vmlinuz, linuxrc, sbin/vgchange, sbin/vgscan, ... and to switch
to the real root after activating the root volume group in linuxrc.
All the rest can be under lvm control.

Basically the lvm driver can take care of reading the VGDA from the
root VG disks at init time.

Regards,
Heinz
--

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

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

^ permalink raw reply	[flat|nested] 25+ messages in thread
* Re: [linux-lvm] RAID and LVM?
@ 1999-07-27 15:37 Heinz Mauelshagen
  0 siblings, 0 replies; 25+ messages in thread
From: Heinz Mauelshagen @ 1999-07-27 15:37 UTC (permalink / raw)
  To: linux-lvm

> 
> On Tue, Jul 27, 1999 at 02:23:53PM +0000, Heinz Mauelshagen wrote:
> > > i believe useful integrating raid and lvm
> > > it means a user can dcide the different raid policy
> ...
> > That's the Veritas Volume Manager concept.
> that is what i am accustomed to.
> i usually work on hp servers.
> are you suggesting there are better ways to do things?

Only different ways 8*)

I like HPs ease of use and concept. It avoids lots of work to
learn LVM administration and to use it in day by day business.
That's the reason why the Linux LVM is similar to HPs.

> 
> > > as a side question, how does LVM autodetect works
> > > (if it exists, that is)?
> 
> > Today, it's the initrd mechanism (partially) supported by lvmcreate_initrd
> > in LVM 0.7.
> that is what i tought, see my previous msg
> but the scan is done in user space, i was asking if some
> kernel space solution existed/was planned/has any sense

If we want to get rid of the initrd constraints there must be a driver
init time solution in the LVM, which is able to autodetect a 'boot' VG 
or at least a LILO parameter telling the LVM driver, which VG to use for boot.

This means on the other hand, that the driver code will be bigger
and therefore more complex than it is today. It's no kernel size issue,
because the code can be thrown away after init.

> 
> what i want to do is have both raid and LVM work and be autodetected
> at boot even if both are compiled as modules.
> why would i want to do this?
> Distributions, i would like both raid and lvm to become
> a standard part of all linux distributions.

I like your opinion ;*)

> 
> i hope that there will be some improvements in
> boot loaders, so we can avoid the small bios addressable
> partition, and completely avoid the idiotic pc partitioning
> cheme.
>

This means LILO^2.

But if you don't keep up with partitions/slices or whatever, you
you should have a kind of header anyway, which carries basic identifying
information about the disks contents/usage.
The information presented by disk firmware today is not sufficient
to avoid accidential misuse of the disk contents.

IMO it's not a big issue to have a small (~8-16m) bios addressable
partition (which could be MD mirrored) to store the kernel and some
neccessary stuff to fire the machine up including MD and LVM.

Regards,
Heinz

--

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

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

^ permalink raw reply	[flat|nested] 25+ messages in thread
[parent not found: <852567BA.0076DBF1.00@USCOMM02.aholdusa.com>]
end of thread, other threads:[~1999-08-03 20:24 UTC | newest]

Thread overview: 25+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
1999-07-14 22:38 [linux-lvm] RAID and LVM? Paul Jakma
1999-07-14 23:04 ` Heinz Mauelshagen
1999-07-14 23:15   ` Paul Jakma
1999-07-20 21:40   ` Paul Jakma
1999-07-21 20:49     ` Luca Berra
1999-07-21 21:22       ` Paul Jakma
1999-07-22  7:48         ` Luca Berra
1999-07-25 22:29           ` Luca Berra
1999-07-26  0:12             ` Paul Jakma
1999-07-26 11:11               ` Luca Berra
1999-07-26 18:54                 ` Paul Jakma
1999-07-26 20:25                   ` Ingo Molnar
1999-07-26 20:52                     ` Paul Jakma
1999-07-27  9:47                     ` Luca Berra
1999-07-28  9:31                       ` Luca Berra
1999-08-02  8:57                   ` James Pattinson
1999-08-02 13:03                     ` Luca Berra
1999-08-02 13:25                       ` James Pattinson
1999-08-02 15:37                         ` Luca Berra
1999-08-02 16:12                         ` S. Ryan Quick
1999-08-02 19:21                         ` Paul Jakma
1999-07-27 12:23 Heinz Mauelshagen
1999-07-27 12:57 ` Luca Berra
1999-07-27 15:37 Heinz Mauelshagen
     [not found] <852567BA.0076DBF1.00@USCOMM02.aholdusa.com>
1999-08-03 20:24 ` Paul Jakma

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