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RE: [dm-devel] LVM Multipathing



Hello,

I seen FAQ. Part relevant to me from FAQ (copied below) consist semething
related to files /etc/mkinitrd/modules and
/etc/mkinitrd/scripts.
But these files are not peresnt at the given location on my system.
I have installed udev-021-36.32 and multipath-tools-0.2.1 ( one which come
bundled with SLES9).
Please let me know why they are not present over. is there something still
missing?
Or i need install something else ( obviously excluding OS)?

	1. How to set up System-on-multipath ?
	======================================

	prerequisite : udev and multipath-tools installed

	here are the steps on a Debian SID system :

	* add dm-mpath and dm-multipath to /etc/mkinitrd/modules
	* copy $tools_dir/multipath/0[12]_* to /etc/mkinitrd/scripts
	* define a friendly alias for your multipathed root disk
	  (in /etc/multipath.conf). Example : "system"
	* enable busybox in /etc/mkinitrd/mkinitrd.conf and set ROOT
	  to any valid block-device (but not a /dev/dm-* one, due to
	  an mkintrd misbelief that all dm-* are managed by LVM2)
	* run mkinitrd
	* in /boot/grub/menu.lst, define the root= kernel parameter
	  Example : root=/dev/system1
	* modify /etc/fstab to reference /dev/system* partitions

	At reboot, you should see some info like :

	path /dev/sda : multipath system
	...
	gpt: 0 slices
	dos: 5 slices
	reduced size of partition #2 to 63
	Added system1 : 0 70685937 linear /dev/system 63
	Added system2 : 0 63 linear /dev/system 7068600
	Added system5 : 0 995967 linear /dev/system 70686063
	...

Thanks and Regards,
Shahid Shaikh.


-----Original Message-----
From: Christophe Varoqui [mailto:christophe varoqui free fr]
Sent: Sunday, February 13, 2005 3:59 PM
To: shahid shaikh patni com; device-mapper development
Subject: Re: [dm-devel] LVM Multipathing


Hello,

This is documented in the multipath-tools' FAQ.
In lvm2.conf, you need to exclude the paths from the scaning, and allow
DM devices to be scaned.

regards,
cvaroqui

shahid shaikh wrote:

>Hi,
>
>I am trying to test multipathing on lvm2.
>
>Configuration that i am using is as below:
>
>OS                     : SLES9 ( kernel 2.6.5)
>lvm                     : lvm2-2.00.15-0.3
>multipath-tools    : multipath-tools-0.2.1
>udev                   : udev-021-36.32
>sysfs                  : sblim-cmpi-sysfs-1.1.5-0.2
>hotplug               : hotplug-0.44-32.21 and hotplugctl-0.08-264.1
>device-mapper     : device-mapper-1.00.09-17.5
>
>I tried following things :
>
>When I dont have multipaths for LUNs:
>1) I tried to create PVs on LUNs using pvcreate
>2) Then VGs using above PVs by command vgcreate
>3) Then I have created some LVs on VGs.
>4) I also fire some I/O on these LVs.
>All aboe commands worked succesfully reflecting changes in pvscan, vgscan
>and lvscan.
>
>When I have multiplepaths to LUNs:
>I tried to create PV on one of the device but on doing pvscan it shows me
>some other device.
>    e.g  My LUN no 5 has for paths so I can see these four paths as
>/dev/sdb, /dev/sdg, /dev/sdl and /dev/sdq.
>          then i did following
>	   linux# pvcreate /dev/sdb
>	   /dev/sdb successfully created
>         linux# pvscan
>	 	Found duplicate PV owucgI06ZCWQHX6rM3Jyj6UKsr5MOt7E: using /dev/sdb not
>/dev/sdq
>		Found duplicate PV owucgI06ZCWQHX6rM3Jyj6UKsr5MOt7E: using /dev/sdg not
>/dev/sdq
>  		Found duplicate PV owucgI06ZCWQHX6rM3Jyj6UKsr5MOt7E: using /dev/sdl not
>/dev/sdq
> 		PV /dev/sdq    VG vg01   lvm2 [1.00 GB / 972.00 MB free]
>  		Total: 1 [1.00 GB] / in use: 1 [1.00 GB] / in no VG: 0 [0   ]
>
>	  linux# vgcreate vg01
>		succesfully created
>
>	  linux# vgscan
> 		Found duplicate PV owucgI06ZCWQHX6rM3Jyj6UKsr5MOt7E: using /dev/sdb not
>/dev/sdq
>		Found duplicate PV owucgI06ZCWQHX6rM3Jyj6UKsr5MOt7E: using /dev/sdg not
>/dev/sdq
>  		Found duplicate PV owucgI06ZCWQHX6rM3Jyj6UKsr5MOt7E: using /dev/sdl not
>/dev/sdq
>
> I tried the same thing with all permutations but i couldnt create a volume
>group.
>
> I also have  multipath-tools-0.3.9 and  multipath-tools-0.4.2.
> But I am not sure whether they will compatible with kernel 2.6.5.
>
>If you can help me in this scenario I will be thankfull to you.
>Please let me know the steps through which I can achieve multipathing on my
>configuration.
>
>Thanks and Regards,
>Shahid Shaikh.
>
>
>
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