Re: [linux-lvm] how can I init LVM on software RAID ?

["Jürgen Frank" <jfrank@lxco.com>]

Hi everyone, Hi Chris 

ok, I think I have a little solution for my problem with the LVM over
SoftwareRaid. It's seems to 
work with the new beta version (sorry I don't try the patch for the
0.9). 
So we have only one little problem, if we boot our system the raid1
(mirror)-system don't start correctly.
(on off the mirror disk isn't running). In that case the lvm don't start
too !?

But I think that's more a problem of the SoftwareRaid , possible it's a
hardware failure of the disk or the disk have a very high startup time.
But I don't understand why lvm don't startup, normally this is a 
transparenc fault , or ?

byebye Juergen


>Chris Worley wrote:
> 
> Jürgen,
> 
> You are correct.  That is a very good question (and valid for this
> newsgroup).  I don't have an answer.  I've seen the documentation that
> says you can make raid 10 & 50 (etc...) by mixing MD's under PV's, as
> well as making VG's out of LVM's (but why?).  I've also seen errors if
> I haven't set my PV's partition to 8e... and there's no way to fdisk
> an MD (to set the partition type).  I would worry about the
> performance of two layers of software overhead below the file system.
> 
> I had barely crawled out of bed when I saw your post and thought "I
> can help a newbie".  This is not a trivial question, I was wrong ;)
> 
> Chris
> 
> Jürgen Frank wrote:
> 
> > Chris Worley wrote:
> >
> >> Jürgen,
> >>
> >> "md" and "lvm" are two different ways of making a software raid.
> >>
> >> lvm only does raid0.  The main purpose of LVM is to allow you to manage
> >> disks underneath the file system... adding and removing disks
> >> dynamically.
> >>
> >
> >
> > Jep, that's the point why I want to use this two systems. So I want to
> > create a RAID 1 / 5 system and on the top I put the LVM. With this
> > method I have a good system with snapshot and enlargment feature !!!
> > And if I read all the docu (the howto, the pdf from sistina) lvm works
> > fine with the md - drives. But, that is the point which I can't follow
> > in the moment. Because I can't make partitions on a md drive and LVM
> > need this partitions ...
> >
> >
> >
> >
> >> There should be HOWTO's for md in your /usr/doc area.  The LVM newsgroup
> >> is not a good place to ask MD related questions.  There are a few
> >> "howto's" for LVM:
> >>
> >> http://www.sistina.com/lvm/Pages/howto.html
> >>
> >> I like:
> >>
> >> http://www.ds9a.nl/lvm-howto/HOWTO//cvs/lvm-howto/lvm-howto.html
> >>
> >> Chris
> >>
> >
> >
> > I read all this docu, but I can't find any help for a system LVM over
> > MD-Drives (Software RAID) !!!
> >
> >
> > Juergen
> >
> >
> >> Jürgen Frank wrote:
> >>
> >>> Hi !!
> >>>
> >>> I want to create the following system :
> >>>
> >>> I use the new kernel (2.4) and I want to use the software raid and the
> >>> lvm,
> >>> but my problem is... how ?
> >>>
> >>> I can't find a step by step documentation and all what I try don't work.
> >>>
> >>> So what did I done :
> >>>
> >>> * create a mirror system with software raid (last version), after this
> >>>   step I have a good raid system with the drive /dev/md0
> >>>
> >>> * normally now I need to create a partition on the drive , but I read in
> >>> the raid docu that the md-drives don't support partitions !!!
> >>>
> >>> But, without a partiton of the type 0x8e I can't run vgscan and
> >>> pvcreate...
> >>>
> >>> So, can anyone help me ?!
> >>>
> >>> Juergen
> >>>
> >>> (sorry for the bad english)
> >>> _______________________________________________
> >>> linux-lvm mailing list
> >>> linux-lvm@sistina.com
> >>> http://lists.sistina.com/mailman/listinfo/linux-lvm
> >>