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Re: [dm-devel] Need Help



Attached document was shared by Chandra for installing RHEL/SLES on
multipath devices.
See if anything helps you.

Regards,
Pradipmaya.

On Jan 17, 2008 10:34 AM, Nath, Varun <varun nath amd com> wrote:
> Hi,
>
> Can you please provide me with the process to add the dm-multipath in
> mkinitrd?
>
> I am sure that those devices are not getting loaded.
>
> Also regarding the fstab, I earlier had the LVM for those LUNs. But
> since I faced the problem of system not booting up, I removed them for
> the time being.
>
> Thanks,
> Varun Nath
>
>
> -----Original Message-----
> From: dm-devel-bounces redhat com [mailto:dm-devel-bounces redhat com]
> On Behalf Of Pradipmaya Maharana
> Sent: Thursday, January 17, 2008 12:25 PM
> To: device-mapper development
> Subject: Re: [dm-devel] Need Help
>
> Could you please share the fstab entry (also what you are trying to add
> to it).
> When are you getting the problem (not recognizing devices), is it at
> boot time?
>
> I am new to Linux but my hunch is when you are booting, as multipath
> is loaded, these devices are not getting recognised. In this case you
> might want to mkinitrd with dm-multipath.
>
> Thanks,
> Pradipmaya.
>
> 2008/1/17 Nath, Varun <varun nath amd com>:
> >
> >
> >
> > Hi,
> >
> >
> >
> > I am trying to configure multipathing on Red hat 4 update 6 64 bit.
> >
> >
> >
> > Below is the list of RPM I have installed
> >
> >
> >
> > rpm -qa | grep mapper
> >
> > device-mapper-1.02.21-1.el4
> >
> > device-mapper-1.02.21-1.el4
> >
> > device-mapper-multipath-0.4.5-27.RHEL4
> >
> >
> >
> > The hardware is Sun x4600 and I am using QLA cards. The system has two
> LUNs
> > presented to it of size 10 GB and size 90 GB
> >
> >
> >
> > There is a problem when I configure file system on it. I am able to
> access
> > and mount the file system. But when I add those entries in /etc/fstab,
> the
> > system would not recognize those devices.
> >
> >
> >
> > Below is the output from multipath command
> >
> >
> >
> > multipath -ll
> >
> > mpath5 (3600508b40010541d00009000065d0000)
> >
> > [size=90 GB][features="1 queue_if_no_path"][hwhandler="0"]
> >
> > \_ round-robin 0 [prio=100][active]
> >
> >  \_ 1:0:0:2 sdd 8:48  [active][ready]
> >
> >  \_ 2:0:0:2 sdh 8:112 [active][ready]
> >
> > \_ round-robin 0 [prio=20][enabled]
> >
> >  \_ 1:0:1:2 sdf 8:80  [active][ready]
> >
> >  \_ 2:0:1:2 sdj 8:144 [active][ready]
> >
> >
> >
> > mpath4 (3600508b40010541d00009000065a0000)
> >
> > [size=10 GB][features="1 queue_if_no_path"][hwhandler="0"]
> >
> > \_ round-robin 0 [prio=100][enabled]
> >
> >  \_ 1:0:1:1 sde 8:64  [active][ready]
> >
> >  \_ 2:0:1:1 sdi 8:128 [active][ready]
> >
> > \_ round-robin 0 [prio=20][enabled]
> >
> >  \_ 1:0:0:1 sdc 8:32  [active][ready]
> >
> >  \_ 2:0:0:1 sdg 8:96  [active][ready]
> >
> >
> >
> >
> >
> > Also, below is my /etc/multipath.conf
> >
> >
> >
> > # This is an example configuration file for device mapper multipath.
> >
> > # For a complete list of the default configuration values, see
> >
> > # /usr/share/doc/device-mapper-multipath-0.4.5/multipath.conf.defaults
> >
> > # For a list of configuration options with descriptions, see
> >
> > #
> /usr/share/doc/device-mapper-multipath-0.4.5/multipath.conf.annotated
> >
> >
> >
> >
> >
> > # Blacklist all devices by default. Remove this to enable multipathing
> >
> > # on the default devices.
> >
> > #devnode_blacklist {
> >
> > #        devnode "*"
> >
> > #}
> >
> >
> >
> > ## Use user friendly names, instead of using WWIDs as names.
> >
> > defaults {
> >
> >         user_friendly_names yes
> >
> >         selector   "round-robin 0"
> >
> > }
> >
> >
> >
> >
> >
> > ## By default, devices with vendor = "IBM" and product = "S/390.*" are
> >
> > ## blacklisted. To enable mulitpathing on these devies, uncomment the
> >
> > ## following lines.
> >
> > #devices {
> >
> > #       device {
> >
> > #               vendor                  "IBM"
> >
> > #               product                 "S/390 DASD ECKD"
> >
> > #               path_grouping_policy    multibus
> >
> > #               getuid_callout          "/sbin/dasdview -j -f /dev/%n"
> >
> > #               path_checker            directio
> >
> > #       }
> >
> > #}
> >
> >
> >
> >
> >
> > ##
> >
> > ## This is a template multipath-tools configuration file
> >
> > ## Uncomment the lines relevent to your environment
> >
> > ##
> >
> > #defaults {
> >
> > #       udev_dir                /dev
> >
> > #       polling_interval        10
> >
> > #       selector                "round-robin 0"
> >
> > #       path_grouping_policy    multibus
> >
> > #       getuid_callout          "/sbin/scsi_id -g -u -s /block/%n"
> >
> > #       prio_callout            /bin/true
> >
> > #       path_checker            readsector0
> >
> > #       rr_min_io               100
> >
> > #       rr_weight               priorities
> >
> > #       failback                immediate
> >
> > #       no_path_retry           fail
> >
> > #       user_friendly_name      yes
> >
> > #}
> >
> > ##
> >
> > ## The wwid line in the following blacklist section is shown as an
> example
> >
> > ## of how to blacklist devices by wwid.  The 3 devnode lines are the
> >
> > ## compiled in default blacklist. If you want to blacklist entire
> types
> >
> > ## of devices, such as all scsi devices, you should use a devnode
> line.
> >
> > ## However, if you want to blacklist specific devices, you should use
> >
> > ## a wwid line.  Since there is no guarantee that a specific device
> will
> >
> > ## not change names on reboot (from /dev/sda to /dev/sdb for example)
> >
> > ## devnode lines are not recommended for blacklisting specific
> devices.
> >
> > ##
> >
> > devnode_blacklist {
> >
> >        wwid 3600508e000000000ed7fb52911133c06
> >
> >         devnode "^(ram|raw|loop|fd|md|sr|scd|st)[0-9]*"
> >
> >         devnode "^hd[a-z]"
> >
> > }
> >
> > #multipaths {
> >
> > #       multipath {
> >
> > #               wwid
> 3600508b4000156d700012000000b0000
> >
> > #               alias                   yellow
> >
> > #               path_grouping_policy    multibus
> >
> > #               path_checker            readsector0
> >
> > #               path_selector           "round-robin 0"
> >
> > #               failback                manual
> >
> > #               rr_weight               priorities
> >
> > #               no_path_retry           5
> >
> > #       }
> >
> > #       multipath {
> >
> > #               wwid                    1DEC_____321816758474
> >
> > #               alias                   red
> >
> > #       }
> >
> > #}
> >
> > #devices {
> >
> > #       device {
> >
> > #               vendor                  "COMPAQ  "
> >
> > #               product                 "HSV110 (C)COMPAQ"
> >
> > #               path_grouping_policy    multibus
> >
> > #               getuid_callout          "/sbin/scsi_id -g -u -s
> /block/%n"
> >
> > #               path_checker            readsector0
> >
> > #               path_selector           "round-robin 0"
> >
> > #               hardware_handler        "0"
> >
> > #               failback                15
> >
> > #               rr_weight               priorities
> >
> > #               no_path_retry           queue
> >
> > #       }
> >
> > #       device {
> >
> > #               vendor                  "COMPAQ  "
> >
> > #               product                 "MSA1000         "
> >
> > #               path_grouping_policy    multibus
> >
> > #       }
> >
> > #}
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > Here is the contents of the /dev/mpath/
> >
> >
> >
> > [root x mpath]# pwd
> >
> > /dev/mpath
> >
> > [root x mpath]# ls -all
> >
> > total 0
> >
> > drwxr-xr-x   2 root root   80 Jan 16 17:34 .
> >
> > drwxr-xr-x  12 root root 5260 Jan 17 08:17 ..
> >
> > lrwxrwxrwx   1 root root    7 Jan 16 17:34 mpath4 -> ../dm-8
> >
> > lrwxrwxrwx   1 root root    7 Jan 16 17:34 mpath5 -> ../dm-9
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > Can anyone please help me with this? I think I am missing some
> configuration
> > on the system which is causing this.
> >
> >
> >
> > Thanks,
> >
> >
> >
> >
> > --
> > dm-devel mailing list
> > dm-devel redhat com
> > https://www.redhat.com/mailman/listinfo/dm-devel
> >
>
> --
> dm-devel mailing list
> dm-devel redhat com
> https://www.redhat.com/mailman/listinfo/dm-devel
>
>
>
>
>
> --
> dm-devel mailing list
> dm-devel redhat com
> https://www.redhat.com/mailman/listinfo/dm-devel
>
4.1. Installation instructions for SLES10

Note: This is tested on SLES10 SP1. If you have any other version, your
mileage may vary.

   1. Install the OS in a device that has multiple paths. Make sure the
root device's "Mount by" option is set to "Device by-id" (this option is
available under "expert partitioner" as "fstab options").
   2. Complete the installation. Let the system boot up in multiuser mode.
Make sure the root device, swap device are all referenced by their by-id
device node entries instead of /dev/sd* type names. If they are not, fix
them first.
   3. Once booted, update /etc/multipath.conf If you have to make changes
to /etc/multipath.conf, make the changes.
      Note: the option "user_friendly_names" is not supported by initrd.
So, if you have user_friendly_names in your /etc/multipath.conf file,
comment it for now, you can uncomment it later.
   4. Enable multipathing by running the following commands
          * chkconfig boot.multipath on

          * chkconfig multipathd on 
   5. Add multipath module to initrd

      Edit the file /etc/sysconfig/kernel and add "dm-multipath" to
INITRD_MODULES". Note: If your storage devices needs a hardware handler,
add the corresponding module to INITRD_MODULES, in addition to
"dm-multipath". For example add "dm-rdac" and "dm-multipath" to support
IBM's DS4K storage devices
   6.  Run mkinitrd
      Note: You can uncomment the user friendly name if you have commented it above.
   7. Reboot 

The system will come up with the root disk on a multipathed device.

Note: You can switch off multipathing to the root device by adding
multipath=off to the kernel command line.

4.2. Installation instructions for RHEL5

Note: This is tested on RHEL5 U1. If you have any other version, your
mileage may vary.

   1. Start the installation with the kernel command line "linux mpath"
          * You will see multipathed devices (/dev/mapper/mpath*) as
          * installation devices. 
   2. Finish the installation.
   3. Reboot.
          * If your boot device does not need multipath.conf and does not
          * have a special hardware handler, then you are done. If you have
          * either of these, follow the steps below. 
   4. Once booted, update multipath.conf file, if needed.
   5. Run mkinitrd, if you need a hardware handler, add it to initrd with --with option.
          * # mkinitrd /boot/initrd.final.img --with=dm-rdac 
   6. Replace the initrd in your grub.conf/lilo.conf/yaboot.conf with the
newly built initrd.
   7. Reboot. 

The system will come up with the root disk on a multipathed device.

Note: You can switch off multipathing to the root device by adding
multipath=off to the kernel command line. Note: By default, RedHat disables
dm-multipath by blacklisting all devices in /etc/multipath.conf. It just
excludes your root device. If you do not see your other multipath devices
through "multipath -ll", then check and fix the blacklist in
/etc/multipath.conf

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