[linux-lvm] snapshot with 2.6.5 kernel

[linux-lvm] snapshot with 2.6.5 kernel

[Karen Shaeffer]

Hello,

I am running a patched 2.6.5 kernel and using lvm2. Everything
looks ok, but the snapshot may be having problems. Else I just
may be ignorant about how to use the snapshot.

Here is what I am doing on a generic X86 server. I create a logical
volume group out of a number of PEs that are properly configured. Then I
create a logical volume. Then I start to dump a very large tar file
into the logical volume. As this tar file is inflating the files into
the logical volume, I then simultaneously create a snapshot volume of
the recently created logical volume. The very large tar archive that
was in the process of inflating its contents continues for a while,
but finally just crashes and hangs at some point.

Am I missunderstanding how to use snapshot here? Or is this just
severly broken software? Any advise is appreciated.

Thanks,
Karen
-- 
 Karen Shaeffer
 Neuralscape, Palo Alto, Ca. 94306
 shaeffer@neuralscape.com  http://www.neuralscape.com

Re: [linux-lvm] snapshot with 2.6.5 kernel

[Heinz Mauelshagen]

On Sun, May 02, 2004 at 11:42:05PM -0700, Karen Shaeffer wrote:
> 
> Hello,
> 
> I am running a patched 2.6.5 kernel and using lvm2. Everything
> looks ok, but the snapshot may be having problems. Else I just
> may be ignorant about how to use the snapshot.
> 
> Here is what I am doing on a generic X86 server. I create a logical
> volume group out of a number of PEs that are properly configured. Then I
> create a logical volume. Then I start to dump a very large tar file
> into the logical volume. As this tar file is inflating the files into
> the logical volume, I then simultaneously create a snapshot volume of
> the recently created logical volume. The very large tar archive that
> was in the process of inflating its contents continues for a while,
> but finally just crashes and hangs at some point.
> 
> Am I missunderstanding how to use snapshot here? Or is this just
> severly broken software? Any advise is appreciated.


You should be able to create a snapshot fine in ythat situation, even though
the creation will happen slow under load.

Can you repeat the case ?
Do you have an oops ? If so, please provide the ksymoops output
for further analysis of the problem.

> 
> Thanks,
> Karen
> -- 
>  Karen Shaeffer
>  Neuralscape, Palo Alto, Ca. 94306
>  shaeffer@neuralscape.com  http://www.neuralscape.com
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

-- 

Regards,
Heinz    -- The LVM Guy --

*** Software bugs are stupid.
    Nevertheless it needs not so stupid people to solve them ***

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

Heinz Mauelshagen                                 Red Hat GmbH
Consulting Development Engineer                   Am Sonnenhang 11
                                                  56242 Marienrachdorf
                                                  Germany
Mauelshagen@RedHat.com                            +49 2626 141200
                                                       FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Re: [linux-lvm] snapshot with 2.6.5 kernel

[Karen Shaeffer]

On Tue, May 11, 2004 at 01:13:22PM +0200, Heinz Mauelshagen wrote:
> On Sun, May 02, 2004 at 11:42:05PM -0700, Karen Shaeffer wrote:
> > 
> > was in the process of inflating its contents continues for a while,
> > but finally just crashes and hangs at some point.
> > 
> > Am I missunderstanding how to use snapshot here? Or is this just
> > severly broken software? Any advise is appreciated.
> 
> 
> You should be able to create a snapshot fine in ythat situation, even though
> the creation will happen slow under load.
> 
> Can you repeat the case ?
> Do you have an oops ? If so, please provide the ksymoops output
> for further analysis of the problem.


Hello Heinz,

Sorry for the delay in responding, but I am very busy.

Yes, the problem is repeatable. The hardware included an external
RAID array that was accessed with the LSI fibre channel HBA, which
I believe is known to be buggy. So, I have removed this hardware
from my test lab and will be conducting additional testing. I will
provide full details, if I encounter additional problems.

BTW, can you please advise me of the time frame for progress with
LVM2 and the 2.6.x kernel. Is a patchset planned to support the
2.6.6 kernel with respect to snapshot?

Also, can you comment on the evms alternative. It seems they already
have a release supporting the 2.6.6 kernel. My understanding is that
this latest evms release is production ready. Can you discuss LVM2's
status in comparison?

Thanks,
Karen
-- 
 Karen Shaeffer
 Neuralscape, Palo Alto, Ca. 94306
 shaeffer@neuralscape.com  http://www.neuralscape.com