If you look up the EVMS manual and the FAQ on their website they give indication that 
if you want to do multipath on root filesystem you have to change things in startup in 
order to get it to work, they have scripts and workarounds for i386 platform and some 
others, but not s390. I was going to look at that and see if i could hack it for s390 
and share with you all.
I'll probobly not work on it until 11/7/04 or 11/8/04 when im back into work.
-Cameron Seader
208-395-8228
[EMAIL PROTECTED]


-----Original Message-----
From: Linux on 390 Port [mailto:[EMAIL PROTECTED] Behalf Of
Robert J Brenneman
Sent: Wednesday, November 03, 2004 8:09 AM
To: [EMAIL PROTECTED]
Subject: Re: Best Practices EVMS FCP Multipathing


Yes - you definately want multipathing for I/O intensive things like
databases. At the moment this is usually only done with things like /home
or /opt since thats what the installers support.

The installers dont really support complex root volumes at the moment, but
setting up a multipathed root could probably be done the hard way:

Install a SLES-9 system on a single path standard SCSI LUN.
configure a multipath EVMS LUN to that system at /mnt
copy the entire file system to the EVMS LUN
chroot into the multipathed LUN and do some config file editing, mkinitrd,
zipl, etc.

I think that as long as the initrd contains the EMVS multipath modules, and
that you always IPL through the same path it should work.

I'll test this theory and let ya'll know how it goes.

Jay Brenneman

Linux Test and Integration Center

T/L:       295 - 7745
Extern: 845 - 435 - 7745
[EMAIL PROTECTED]




                                                                       
             Martin Peschke3                                           
             <[EMAIL PROTECTED]                                         
             COM>                                                       To
             Sent by: Linux on         [EMAIL PROTECTED]         
             390 Port                                                   cc
             <[EMAIL PROTECTED]                                         
             IST.EDU>                                              Subject
                                       Re: Best Practices EVMS FCP     
                                       Multipathing                    
             02/11/2004 04:30                                          
             PM                                                        
                                                                       
                                                                       
             Please respond to                                         
             Linux on 390 Port                                         
                                                                       
                                                                       




Cameron,

yes, I have tried to install SLES9 on a multipathed SCSI disk: it all wound
up in disaster.
There are no clear directions when one tries to achieve that using YaST
(there is md, LVM, and EVMS), not to mention scarce documentation.
I finally managed to create some multipathing configuration using md, that
didn't look too insane to me.
I clicked 'ok' when a YaST message appeared that warned me that my
multipath setup might not come up during IPL in some cases. Then the
installation crashed (oops in md?).
My personal conclusion is: no, multipathed boot devices are not supported.
Though it might be worth trying to setup a multipathed root device, using a
miniature (non-multipathed) boot device.
For the rest, I agree with Carsten.

Mit freundlichen Gr��en / with kind regards

Martin Peschke

IBM Deutschland Entwicklung GmbH
Linux for zSeries Development
Phone: +49-(0)7031-16-2349




                      Carsten Otte
                                               To:      Linux on 390 Port
<[EMAIL PROTECTED]>
                      02/11/2004 20:57         cc:      Stefan
Bader/Germany/[EMAIL PROTECTED], Martin Peschke3/Germany/[EMAIL PROTECTED]
                                               From:    Carsten
Otte/Germany/[EMAIL PROTECTED]
                                               Subject: Re: Best Practices
EVMS FCP Multipathing(Document link: Martin Peschke3)





Hi Cameron,

you definetly want to do multipathing with FCP. Unlike with FICON, your
adapter (and your physical fibre) will be a single point of failure if you
don't. In order to maximize performance, you can combine multipathing with
raid0 striping to gain further.

with kind regards
Carsten Otte
--
omnis enim res, quae dando non deficit, dum habetur et non datur, nondum
habetur, quomodo habenda est



                      "Seader, Cameron"
                      <[EMAIL PROTECTED]        To:
[EMAIL PROTECTED]
                      er.com>                  cc:
                      Sent by: Linux on        Subject:  Best Practices
EVMS FCP Multipathing
                      390 Port
                      <[EMAIL PROTECTED]
                      IST.EDU>


                      02/11/2004 01:40
                      AM
                      Please respond to
                      Linux on 390 Port





Greetings,
Just a few Questions reguarding FCP Multipathing. I have installed multiple
systems with a 5 GB LUN for the / system and am wondering if it is a good
idea to define this with multipathing, or is it better to add more disks to
the mix and multipath those that are only  used for say databases and such?
What is the best practice for this. Is it a good idea to have multipathing
on your root volume or not? Novell does not seem to know either. They are
hinting at the idea a bit that there would be more problems if you had the
root volume setup with multipathing. Any ideas? What do you think? Has
anyone had any experiences with this that they would like to share?

-Cameron Seader


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