[linux-lvm] SuSE 9.0 and LVM2

[linux-lvm] SuSE 9.0 and LVM2

[Avtar Gill]

This is a general question to anyone out there currently using
LVM2 with SuSE Professional 9.0 on production servers (or
workstations). Would you be kind enough to share your experiences
with the rest of us? Did you experience any minor or major issues
along the way? SuSE 9.0 ships with LVM 1.* by default but I thought
it might be a good idea to implement new servers with LVM 2.*
instead so upgrading to future versions of SuSE (with kernel 2.6)
will be less of a hassle. Any thoughts or comments?

Re: [linux-lvm] SuSE 9.0 and LVM2

[Rainer Krienke]

[-- Attachment #1: signed data --]
[-- Type: text/plain, Size: 2782 bytes --]

On Mittwoch, 11. Februar 2004 23:23, Avtar Gill wrote:
> This is a general question to anyone out there currently using
> LVM2 with SuSE Professional 9.0 on production servers (or
> workstations). Would you be kind enough to share your experiences
> with the rest of us? Did you experience any minor or major issues
> along the way? SuSE 9.0 ships with LVM 1.* by default but I thought
> it might be a good idea to implement new servers with LVM 2.*
> instead so upgrading to future versions of SuSE (with kernel 2.6)
> will be less of a hassle. Any thoughts or comments?
>

We are running LVM2 on a suse8.2 system using the suse9.0 kernel (2.4.21-166).  
The lvm2 utilities (version 2.2.00.05) are in this case not taken from suse 
RPMs. I compiled them myself. The system (actualy 3 hosts with a total of ~3 
Hardware  RAIDs, configured with raid level 5) is a NFS and SMB fileserver 
with a total of 3 TBytes storage. Actually the RAIDs offer a total of  ~6 TB 
but we do mirroring so we can only use have of the real size. 

LVM sits on top of a md device hierachy: The hardware RAIDs are connected by 
fibrechannel using 2 seperate paths from each raid array to each host across 
2 fc switches. So each host has first two multipath md devices and on top of 
this it has a raid1 md device (mirror) that performs mirroring across the 
raids so that even if one complete RAID should fail nothing serious will 
happen. This redundency already proved quite useful since we can take one 
hardware RAID out of order eg for a firmware upgrade we had to do lately 
without stopping the servers in doing their job. 

The md mirror each hosts sees is used as physical volume for LVM. Here LVM2 
proved very useful since it allowed me to configure the (md) devices LVM 
should scan for volumes when starting. I first tried using LVM1 in this 
system, but this failed since LVM1 was confused since during scanning the 
disks it saw the volumegroup and the volumes several times (probably due to 
the multipath and mirroring md devices pointing to the same data) and this 
lead to a complete loss of the logical volumes with all the data inside.

The filesystem in use on the local volumes is xfs. 

The system is running about 6 months now, and we did not have any trouble with 
it.

Have a nice day
Rainer
-- 
---------------------------------------------------------------------------
Rainer Krienke, Universitaet Koblenz, Rechenzentrum, Raum A022
Universitaetsstrasse 1, 56070 Koblenz, Tel: +49 261287 -1312, Fax: -1001312
Mail: krienke@uni-koblenz.de, Web: http://www.uni-koblenz.de/~krienke
Get my public PGP key: http://www.uni-koblenz.de/~krienke/mypgp.html
---------------------------------------------------------------------------

[-- Attachment #2: signature --]
[-- Type: application/pgp-signature, Size: 189 bytes --]

Re: [linux-lvm] SuSE 9.0 and LVM2

[Heinz Mauelshagen]

On Thu, Feb 12, 2004 at 08:40:54AM +0100, Rainer Krienke wrote:
Content-Description: signed data
> On Mittwoch, 11. Februar 2004 23:23, Avtar Gill wrote:
> > This is a general question to anyone out there currently using
> > LVM2 with SuSE Professional 9.0 on production servers (or
> > workstations). Would you be kind enough to share your experiences
> > with the rest of us? Did you experience any minor or major issues
> > along the way? SuSE 9.0 ships with LVM 1.* by default but I thought
> > it might be a good idea to implement new servers with LVM 2.*
> > instead so upgrading to future versions of SuSE (with kernel 2.6)
> > will be less of a hassle. Any thoughts or comments?
> >
> 
> We are running LVM2 on a suse8.2 system using the suse9.0 kernel (2.4.21-166).  
> The lvm2 utilities (version 2.2.00.05) are in this case not taken from suse 
> RPMs. I compiled them myself. The system (actualy 3 hosts with a total of ~3 
> Hardware  RAIDs, configured with raid level 5) is a NFS and SMB fileserver 
> with a total of 3 TBytes storage. Actually the RAIDs offer a total of  ~6 TB 
> but we do mirroring so we can only use have of the real size. 
> 
> LVM sits on top of a md device hierachy: The hardware RAIDs are connected by 
> fibrechannel using 2 seperate paths from each raid array to each host across 
> 2 fc switches. So each host has first two multipath md devices and on top of 
> this it has a raid1 md device (mirror) that performs mirroring across the 
> raids so that even if one complete RAID should fail nothing serious will 
> happen. This redundency already proved quite useful since we can take one 
> hardware RAID out of order eg for a firmware upgrade we had to do lately 
> without stopping the servers in doing their job. 
> 
> The md mirror each hosts sees is used as physical volume for LVM. Here LVM2 
> proved very useful since it allowed me to configure the (md) devices LVM 
> should scan for volumes when starting. I first tried using LVM1 in this 
> system, but this failed since LVM1 was confused since during scanning the 
> disks it saw the volumegroup and the volumes several times (probably due to 
> the multipath and mirroring md devices pointing to the same data) and this 
> lead to a complete loss of the logical volumes with all the data inside.

Yes, LVM1 copes with 1 MD (eg, RAID1) stacked below it quite well.
It hasn't been engineered to cope with more levels (eg, your RAID1+multipath)
though.

LVM2 as you pointed out, is capable to set up device name filters to
cope with any such multi-level stacks avoiding access to device nodes
you don't like it to access.

Regards,
Heinz    -- The LVM Guy --

> 
> The filesystem in use on the local volumes is xfs. 
> 
> The system is running about 6 months now, and we did not have any trouble with 
> it.
> 
> Have a nice day
> Rainer
> -- 
> ---------------------------------------------------------------------------
> Rainer Krienke, Universitaet Koblenz, Rechenzentrum, Raum A022
> Universitaetsstrasse 1, 56070 Koblenz, Tel: +49 261287 -1312, Fax: -1001312
> Mail: krienke@uni-koblenz.de, Web: http://www.uni-koblenz.de/~krienke
> Get my public PGP key: http://www.uni-koblenz.de/~krienke/mypgp.html
> ---------------------------------------------------------------------------

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

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

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