Re: [Evms-devel] Possible to create a degraded RAID5 array withEVMS?

[James L. <jam...@ho...>]

I should have mentioned: the version of mdadm I was using is the default 
version which ships with Ubuntu: 1.11.0.

And I was using version 0.9 superblocks (both for the mdadm arrays, and for 
the arrays created by EVMS).  Is there an advantage to using a version 1.0 
superblock rather than the older 0.9 versions?

I'll give this another go after wiping the hard drive completely.... I'm 
really hoping to get this sorted out soon, as I'm completely out of space; 
despite having some 320GB drives sitting spare....

By the way, I've put up a feature request for EVMS to allow creating 
degraded RAID5 arrays (which would get me past all these problems), which 
would really be nice.  I might have a look and see if it seems hard to do 
(if it's a simple change I might just make it and recompile...).


>From: Mike Tran <mh...@us...>
>To: evm...@li...
>Subject: Re: [Evms-devel] Possible to create a degraded RAID5 array 
>withEVMS?
>Date: Mon, 28 Nov 2005 16:58:39 -0600
>
>On Sat, 2005-11-26 at 14:42, James Lee wrote:
> > Hi there,
> >
> > I'm having some more trouble with getting EVMS and mdadm to play nicely
> > together (even after upgrading EVMS)...
> >
> > The steps I'm taking are:
> >
> > 1. Starting with an empty drive (wiped it by zero-filling the start and 
>end
> > of drive to make sure there's no residual partition table information).
> > Create two logical partitions (/dev/sdb5 and /dev/sdb6).
> >
> > 2. Use mdadm to create a degraded "3-drive" RAID5 array called /dev/md0:
> > "mdadm --create /dev/md0 --level=5 --raid-devices=3 /dev/sdb5 /dev/sdb6
> > missing".
> >
> > 3. Start EVMS.  It correctly detects the degraded RAID5 array on 
>/dev/md0.
> >
> > 4. In EVMS, create 4 partitions on /dev/sdb, each one just over half the
> > size of the partitions in the RAID5 array.  Create two 2-drive RAID0
> > stripes, from these partitions.
> >
> > 5. Add one of these RAID0 arrays to the RAID5 array.  Wait for it to 
>resync.
> >   RAID5 array is now active and non-degraded.
> >
> > 6. Create an EXT3 filesystem and bung some files on it.
> >
> > 7. Everything working fine so far.  Now expand the RAID5 array with the
> > other RAID0 array.  This seems to work fine.  No data lost on the 
>partition
> > and no errors.
> >
> > 8. Reboot.  When next starting EVMS, I get the following errors:
> >
>
>In theory, this should work!!! I will try your scenario to find out what
>went wrong.
>
>--
>Mike T.
>
>
>
>
>
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