Installing RHEL with single controller

Installing RHEL with single controller

[Pradipmaya Maharana]

Hi All,

I installed RHEL on a blade with only one LUN and with only one controller up.
So for obvious reasons, even though I specified the option "linux
mpath" for installer, the only device available for partition was
/dev/sda/.
I letthe installaer to create default partition, that is LVM based partition.

Later, after everything goes well, I addthe second controller and then
reboot the blade, butu multipath was not configured on any of the
devices (root, boot or swap).

I modified the /etc/fstab file to mount the /boot by device id (this
was the only device that was referring to /dev/sda) and rebooted, but
still no luck.

What am I missing here? How do I configure multipath on /root.

Thanks and Regards,
Pradipmaya.

Re: Installing RHEL with single controller

[malahal]

Pradipmaya Maharana [pradipmaya@gmail.com] wrote:
> Hi All,
> 
> I installed RHEL on a blade with only one LUN and with only one controller up.
> So for obvious reasons, even though I specified the option "linux
> mpath" for installer, the only device available for partition was
> /dev/sda/.

Don't know what the installer does in this case, so check your initrd if
multipath is enabled. If not, there should be a way to generate
multipath capable initrd by running 'mkinitrd'. You may need to update
some files before running mkinitrd to poduce multipath capable initrd...

--Malahal.

Re: Installing RHEL with single controller

[Pradipmaya Maharana]

Multipath is getting loaded, if that is what you are wondering about.
After reboot I check for multipathd status, and smod for the modules
loaded, everything looks fine.

Moreover, if I try to run multipath -ve, it would fail with domap (0) failed.
/var/log/messages would say "error getting device".
I was thinking that I get this error because OS is already loaded on
the device I am trying to configure multipath for.

What do you suggest.

Thanks and Regards,
Pradipmaya.


On Thu, Feb 28, 2008 at 11:21 AM,  <malahal@us.ibm.com> wrote:
> Pradipmaya Maharana [pradipmaya@gmail.com] wrote:
> > Hi All,
> >
> > I installed RHEL on a blade with only one LUN and with only one controller up.
> > So for obvious reasons, even though I specified the option "linux
> > mpath" for installer, the only device available for partition was
> > /dev/sda/.
>
> Don't know what the installer does in this case, so check your initrd if
> multipath is enabled. If not, there should be a way to generate
> multipath capable initrd by running 'mkinitrd'. You may need to update
> some files before running mkinitrd to poduce multipath capable initrd...
>
> --Malahal.
>
> --
> dm-devel mailing list
> dm-devel@redhat.com
> https://www.redhat.com/mailman/listinfo/dm-devel
>

Re: Installing RHEL with single controller

[malahal]

Pradipmaya Maharana [pradipmaya@gmail.com] wrote:
> Multipath is getting loaded, if that is what you are wondering about.
> After reboot I check for multipathd status, and smod for the modules
> loaded, everything looks fine.

No, I am asking if initrd image contains multipath commands. You need to
use cpio to extract the initrd image and see the source code to check
it!

multipath has to be loaded and *run* before mounting your real root. If
it gets loaded after  mounting your real root, it is too late to have
multipath on root disk! Looks like you need to regenerate initrd with
multpath support.

--Malahal.

Re: Installing RHEL with single controller

[Chandra Seetharaman]

On Thu, 2008-02-28 at 12:11 -0800, malahal@us.ibm.com wrote:
> Pradipmaya Maharana [pradipmaya@gmail.com] wrote:
> > Multipath is getting loaded, if that is what you are wondering about.
> > After reboot I check for multipathd status, and smod for the modules
> > loaded, everything looks fine.
> 
> No, I am asking if initrd image contains multipath commands. You need to
> use cpio to extract the initrd image and see the source code to check
> it!
> 
> multipath has to be loaded and *run* before mounting your real root. If
> it gets loaded after  mounting your real root, it is too late to have
> multipath on root disk! Looks like you need to regenerate initrd with
> multpath support.

Yes, Malahal is right. You need to create initrd with multipath tools.
You can do this by running mkinitrd with "--with=dm-multipath"
(Follow the SLES10 installation instructions in my documentation
http://sources.redhat.com/lvm2/wiki/MultipathUsageGuide )


> --Malahal.
> 
> --
> dm-devel mailing list
> dm-devel@redhat.com
> https://www.redhat.com/mailman/listinfo/dm-devel
-- 

----------------------------------------------------------------------
    Chandra Seetharaman               | Be careful what you choose....
              - sekharan@us.ibm.com   |      .......you may get it.
----------------------------------------------------------------------

Re: Installing RHEL with single controller

[Pradipmaya Maharana]

Thanks Malahal/Chandra. I will try this and let you know.

Thanks again,
Pradipmaya.


On Thu, Feb 28, 2008 at 1:36 PM, Chandra Seetharaman
<sekharan@us.ibm.com> wrote:
> On Thu, 2008-02-28 at 12:11 -0800, malahal@us.ibm.com wrote:
> > Pradipmaya Maharana [pradipmaya@gmail.com] wrote:
> > > Multipath is getting loaded, if that is what you are wondering about.
> > > After reboot I check for multipathd status, and smod for the modules
> > > loaded, everything looks fine.
> >
> > No, I am asking if initrd image contains multipath commands. You need to
> > use cpio to extract the initrd image and see the source code to check
> > it!
> >
> > multipath has to be loaded and *run* before mounting your real root. If
> > it gets loaded after  mounting your real root, it is too late to have
> > multipath on root disk! Looks like you need to regenerate initrd with
> > multpath support.
>
> Yes, Malahal is right. You need to create initrd with multipath tools.
> You can do this by running mkinitrd with "--with=dm-multipath"
> (Follow the SLES10 installation instructions in my documentation
> http://sources.redhat.com/lvm2/wiki/MultipathUsageGuide )
>
>
> > --Malahal.
> >
> > --
> > dm-devel mailing list
> > dm-devel@redhat.com
> > https://www.redhat.com/mailman/listinfo/dm-devel
> --
>
> ----------------------------------------------------------------------
>    Chandra Seetharaman               | Be careful what you choose....
>              - sekharan@us.ibm.com   |      .......you may get it.
> ----------------------------------------------------------------------
>
>
>
> --
> dm-devel mailing list
> dm-devel@redhat.com
> https://www.redhat.com/mailman/listinfo/dm-devel
>

Re: Installing RHEL with single controller

[Pradipmaya Maharana]

Ok; this is what I did:

mkinitrd   /boot/initrd.final.img   2.6.18-53.el5xen   --with=dm-multipath

Changed the /boot/grub/menu.lst file to point to new initrd image file.
Reboot is fine but multipath -ll is still null. :(

What am I missing here.

Regards,
Pradipmaya.


On Thu, Feb 28, 2008 at 1:36 PM, Chandra Seetharaman
<sekharan@us.ibm.com> wrote:
> On Thu, 2008-02-28 at 12:11 -0800, malahal@us.ibm.com wrote:
> > Pradipmaya Maharana [pradipmaya@gmail.com] wrote:
> > > Multipath is getting loaded, if that is what you are wondering about.
> > > After reboot I check for multipathd status, and smod for the modules
> > > loaded, everything looks fine.
> >
> > No, I am asking if initrd image contains multipath commands. You need to
> > use cpio to extract the initrd image and see the source code to check
> > it!
> >
> > multipath has to be loaded and *run* before mounting your real root. If
> > it gets loaded after  mounting your real root, it is too late to have
> > multipath on root disk! Looks like you need to regenerate initrd with
> > multpath support.
>
> Yes, Malahal is right. You need to create initrd with multipath tools.
> You can do this by running mkinitrd with "--with=dm-multipath"
> (Follow the SLES10 installation instructions in my documentation
> http://sources.redhat.com/lvm2/wiki/MultipathUsageGuide )
>
>
> > --Malahal.
> >
> > --
> > dm-devel mailing list
> > dm-devel@redhat.com
> > https://www.redhat.com/mailman/listinfo/dm-devel
> --
>
> ----------------------------------------------------------------------
>    Chandra Seetharaman               | Be careful what you choose....
>              - sekharan@us.ibm.com   |      .......you may get it.
> ----------------------------------------------------------------------
>
>
>
> --
> dm-devel mailing list
> dm-devel@redhat.com
> https://www.redhat.com/mailman/listinfo/dm-devel
>

Re: Installing RHEL with single controller

[Chandra Seetharaman]

On Thu, 2008-02-28 at 15:07 -0800, Pradipmaya Maharana wrote:
> Ok; this is what I did:
> 
> mkinitrd   /boot/initrd.final.img   2.6.18-53.el5xen   --with=dm-multipath
> 
> Changed the /boot/grub/menu.lst file to point to new initrd image file.
> Reboot is fine but multipath -ll is still null. :(
> 
> What am I missing here.

That is odd!!

What version of RHEL do you have ?

Do you see 2 scsi devices (sda and sdb) for the same lun when your
system is up ?

Can you send the o/p of mkinitrd.

Can you extract the file "init" from your initrd image and send it.

Can you check if the device is blacklisted in your multipath.conf file ?

> 
> Regards,
> Pradipmaya.
> 
> 
> On Thu, Feb 28, 2008 at 1:36 PM, Chandra Seetharaman
> <sekharan@us.ibm.com> wrote:
> > On Thu, 2008-02-28 at 12:11 -0800, malahal@us.ibm.com wrote:
> > > Pradipmaya Maharana [pradipmaya@gmail.com] wrote:
> > > > Multipath is getting loaded, if that is what you are wondering about.
> > > > After reboot I check for multipathd status, and smod for the modules
> > > > loaded, everything looks fine.
> > >
> > > No, I am asking if initrd image contains multipath commands. You need to
> > > use cpio to extract the initrd image and see the source code to check
> > > it!
> > >
> > > multipath has to be loaded and *run* before mounting your real root. If
> > > it gets loaded after  mounting your real root, it is too late to have
> > > multipath on root disk! Looks like you need to regenerate initrd with
> > > multpath support.
> >
> > Yes, Malahal is right. You need to create initrd with multipath tools.
> > You can do this by running mkinitrd with "--with=dm-multipath"
> > (Follow the SLES10 installation instructions in my documentation
> > http://sources.redhat.com/lvm2/wiki/MultipathUsageGuide )
> >
> >
> > > --Malahal.
> > >
> > > --
> > > dm-devel mailing list
> > > dm-devel@redhat.com
> > > https://www.redhat.com/mailman/listinfo/dm-devel
> > --
> >
> > ----------------------------------------------------------------------
> >    Chandra Seetharaman               | Be careful what you choose....
> >              - sekharan@us.ibm.com   |      .......you may get it.
> > ----------------------------------------------------------------------
> >
> >
> >
> > --
> > dm-devel mailing list
> > dm-devel@redhat.com
> > https://www.redhat.com/mailman/listinfo/dm-devel
> >
-- 

----------------------------------------------------------------------
    Chandra Seetharaman               | Be careful what you choose....
              - sekharan@us.ibm.com   |      .......you may get it.
----------------------------------------------------------------------

Re: Installing RHEL with single controller

[Pradipmaya Maharana]

Any comments?
Please help.

Regards,
Pradipmaya.


On Fri, Feb 29, 2008 at 12:34 PM, Pradipmaya Maharana
<pradipmaya@gmail.com> wrote:
> Hey Chandra,
>
> It's RHEL 5.1.
> [root@localhost test]# uname -a
> Linux localhost.localdomain 2.6.18-53.el5xen #1 SMP Wed Oct 10
> 16:48:44 EDT 2007 x86_64 x86_64 x86_64 GNU/Linux
>
> Yes, it can see the 2 devices.
> [root@localhost test]# cat /proc/partitions
> major minor  #blocks  name
>   8     0   34603520 sda
>   8     1     104391 sda1
>   8     2   34491555 sda2
>   8    16   34603520 sdb
>  253     0   32440320 dm-0
>  253     1    2031616 dm-1
>
> mkinitrd does not return any message.
> [root@localhost ~]# mkinitrd /boot/initrd.final.2.img 2.6.18-53.el5xen
> --with=dm-multipath
> [root@localhost ~]#
>
> Here is what I did:
> [root@localhost test]# cpio -i < initrd.final.2.img
> 15587 blocks
> [root@localhost test]# ls
> bin  dev  etc  init  initrd.final.2.img  lib  proc  sbin  sys  sysroot
> [root@localhost test]# ls lib/
> dm-mirror.ko           ext3.ko                ohci-hcd.ko
> dm-mod.ko              firmware/              scsi_mod.ko
> dm-multipath.ko        jbd.ko                 scsi_transport_sas.ko
> dm-snapshot.ko         mptbase.ko             sd_mod.ko
> dm-zero.ko             mptsas.ko              uhci-hcd.ko
> ehci-hcd.ko            mptscsih.ko            usb-storage.ko
>
> Attached is the init file for your reference.
>
> Here is the blacklist section from /etc/multipath
>
> blacklist {
>        devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"
>        devnode "^(hd|xvd)[a-z][[0-9]*]"
>        devnode "^cciss!c[0-9]d[0-9]*[p[0-9]*]"
> }
>
> Thanks and Regards,
> Pradipmaya.
>
> On Thu, Feb 28, 2008 at 4:15 PM, Chandra Seetharaman
>
> <sekharan@us.ibm.com> wrote:
> > On Thu, 2008-02-28 at 15:07 -0800, Pradipmaya Maharana wrote:
> >  > Ok; this is what I did:
> >  >
> >  > mkinitrd   /boot/initrd.final.img   2.6.18-53.el5xen   --with=dm-multipath
> >  >
> >  > Changed the /boot/grub/menu.lst file to point to new initrd image file.
> >  > Reboot is fine but multipath -ll is still null. :(
> >  >
> >  > What am I missing here.
> >
> >  That is odd!!
> >
> >  What version of RHEL do you have ?
> >
> >  Do you see 2 scsi devices (sda and sdb) for the same lun when your
> >  system is up ?
> >
> >  Can you send the o/p of mkinitrd.
> >
> >  Can you extract the file "init" from your initrd image and send it.
> >
> >  Can you check if the device is blacklisted in your multipath.conf file ?
> >
> >
> >
> >  >
> >  > Regards,
> >  > Pradipmaya.
> >  >
> >  >
> >  > On Thu, Feb 28, 2008 at 1:36 PM, Chandra Seetharaman
> >  > <sekharan@us.ibm.com> wrote:
> >  > > On Thu, 2008-02-28 at 12:11 -0800, malahal@us.ibm.com wrote:
> >  > > > Pradipmaya Maharana [pradipmaya@gmail.com] wrote:
> >  > > > > Multipath is getting loaded, if that is what you are wondering about.
> >  > > > > After reboot I check for multipathd status, and smod for the modules
> >  > > > > loaded, everything looks fine.
> >  > > >
> >  > > > No, I am asking if initrd image contains multipath commands. You need to
> >  > > > use cpio to extract the initrd image and see the source code to check
> >  > > > it!
> >  > > >
> >  > > > multipath has to be loaded and *run* before mounting your real root. If
> >  > > > it gets loaded after  mounting your real root, it is too late to have
> >  > > > multipath on root disk! Looks like you need to regenerate initrd with
> >  > > > multpath support.
> >  > >
> >  > > Yes, Malahal is right. You need to create initrd with multipath tools.
> >  > > You can do this by running mkinitrd with "--with=dm-multipath"
> >  > > (Follow the SLES10 installation instructions in my documentation
> >  > > http://sources.redhat.com/lvm2/wiki/MultipathUsageGuide )
> >  > >
> >  > >
> >  > > > --Malahal.
> >  > > >
> >  > > > --
> >  > > > dm-devel mailing list
> >  > > > dm-devel@redhat.com
> >  > > > https://www.redhat.com/mailman/listinfo/dm-devel
> >  > > --
> >  > >
> >  > > ----------------------------------------------------------------------
> >  > >    Chandra Seetharaman               | Be careful what you choose....
> >  > >              - sekharan@us.ibm.com   |      .......you may get it.
> >  > > ----------------------------------------------------------------------
> >  > >
> >  > >
> >  > >
> >  > > --
> >  > > dm-devel mailing list
> >  > > dm-devel@redhat.com
> >  > > https://www.redhat.com/mailman/listinfo/dm-devel
> >  > >
> >  --
> >
> >
> >
> >  ----------------------------------------------------------------------
> >     Chandra Seetharaman               | Be careful what you choose....
> >               - sekharan@us.ibm.com   |      .......you may get it.
> >  ----------------------------------------------------------------------
> >
> >
> >
>