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

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

Just to follow this up by the way, I put up a request to have EVMS 2.5.3 
backported to the latest stable Ubuntu (Breezy Badger), and it's been 
accepted.  It's now available in the Breezy backports repository.

I'll upgrade and let you know if these problems are fixed...

James


>From: Steve Dobbelstein <st...@us...>
>To: "James Lee" <jam...@ho...>
>CC: evm...@li...
>Subject: Re: [Evms-devel] Possible to create a degraded RAID5 array with 
>EVMS?
>Date: Mon, 21 Nov 2005 11:58:03 -0600
>
>"James Lee" <jam...@ho...> wrote on 11/18/2005 05:52:35 PM:
>
>Hi, James.
>
> > Well I've tried doing this again, this time using the standard Linux
> > partition types.  I started by wiping all the partitions on the drive
>(using
> > cfdisk).  I then created the new partitions with cfdisk, and loaded up
>EVMS
> > to make sure it was OK (I hadn't tried to create any RAID volumes yet).
> >
> > EVMS comes up with some warnings about not being able to assemble some
>RAID
> > arrys.  These arrays should not longer exists; I don't know where EVMS 
>is
>
> > picking them up from?  Do I need to do something more than just wiping
> > partitions to get rid of RAID information on a drive?  Or does EVMS 
>store
>
> > configuration in a config file rather than redetecting it each time?
>
>The metadata for MD devices is stored near the end of the device.  (Round
>the end of the device down to a 64KB boundary, then put the metadata at the
>start of the 64KB block just before the previously calculated 64KB
>boundary.)  My guess is that you recreate the partitions to be the same
>size.  EVMS then found the leftover MD metadata at the end of the
>partitions.
>
> > Anyway, EVMS then gets very confused about these RAID arrays, and on
>exiting
> > I get the following error (and the process hangs):
> >
> > *** glibc detected *** corrupted double-linked list: 0x081a88a0 ***
> >
> > I've attached the debug information for this.  Hopefully it might prove
> > helpful.
>
>Judging from the last lines in the log, it looks like it got tripped up on
>a free().  (Different place in the code that the previous log you sent, but
>on a free() nonetheless)  However, the log is missing the debug information
>for the memory allocations.  Did you rebuild EVMS after running
>"./configure --with-debug <your-other-options>"? The debug version of the
>memory allocation code should catch a double free.  Did you run with the
>debug level set to "everything" (e.g., "evmsgui -d everything")?  It would
>be helpful to have the history of memory allocations and frees in the log.
>
> > I have to say I'm somewhat concerned about these errors.... how
> > stable is the RAID5 code in EVMS considered compared to, say, mdadm?
>Don't
> > get me wrong though, I'm very impressed with EVMS overall :)
>
>The EVMS MD plug-in went through a significant overhaul in order to add
>support for the version 1 MD superblock.  Naturally, some stability was
>lost in the rework.  The bugs are being found and fixed.
>
>Steve D.
>