[dm-devel] Detecting Multiple Paths to LU
shahid shaikh
shahid.shaikh at patni.com
Thu Feb 17 07:39:48 UTC 2005
Hi Coates,
Thanks for the information.I am close to the solution now.
>>Once you assembled the multipath devices you can then run pvcreate
/dev/mapper/XXXXX and create your volume groups.
But the only thing i am unable to understand is that how would I assemble
the multipath device?
who will do this for us LVM2 or Device mapper and how?
What are the steps I need to follow? What argument should I provide to
pvcreate as I had already filtered "sd" devices?
How would I create my assembled device "/dev/mapper/XXXXX"?
It would be very helpful if you could tell me what are the steps to create
assembled device "/dev/mapper/XXXXX". How this assembled device is mapped to
the underlying "sd" devices?
Regards
Shahid Shaikh.
-----Original Message-----
From: Guy Coates [mailto:gmpc at sanger.ac.uk]
Sent: Wednesday, February 16, 2005 7:53 PM
To: shahid.shaikh at patni.com; device-mapper development
Cc: Christophe Varoqui (E-mail); Sandhya Suman (E-mail)
Subject: Re: [dm-devel] Detecting Multiple Paths to LU
You need to set up lvm.conf to do the following. It probably is totally
correct, but it seems to work well enough.
# Make lvm look at the multipath device maps only, not the
# single devices
scan = [ "/dev/mapper" ]
# exclude the raw disks, just to be paranoid
filter = ["r|/dev/sd|"]
# make lvm use dm devices
types = [ "device-mapper", 16 ]
Once you assembled the multipath devices you can then run
pvcreate /dev/mapper/XXXXX
and create your volume groups.
I've created and then extended and LVM across two multipathed physical
volumes on my test system.
--- Volume group ---
VG Name web409mysqltest
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 1
Max PV 0
Cur PV 2
Act PV 2
VG Size 199.99 GB
PE Size 4.00 MB
Total PE 51198
Alloc PE / Size 51198 / 199.99 GB
Free PE / Size 0 / 0
VG UUID CzUDTb-KpRz-KNLS-U24P-5TmZ-4WLN-OSjGBB
--- Logical volume ---
LV Name /dev/web409mysqltest/mysqltest1
VG Name web409mysqltest
LV UUID tT9PHO-1UVt-RsNN-6iFM-KgQx-Gl9r-adck9U
LV Write Access read/write
LV Status available
# open 2
LV Size 199.99 GB
Current LE 51198
Segments 2
Allocation inherit
Read ahead sectors 0
Block device 254:16
--- Physical volumes ---
PV Name /dev/mapper/3600508b40001417e0001c00001b60000
PV UUID 3QvL3p-t45P-AY4x-nIHp-C44s-IM6O-2Ymuwy
PV Status allocatable
Total PE / Free PE 25599 / 0
PV Name /dev/mapper/3600508b40001417e0001c00001c90000
PV UUID QGEVaA-W3sJ-DkLB-Ble1-13sU-bL6u-3tNy78
PV Status allocatable
Total PE / Free PE 25599 / 0
/sbin/dmsetup status /dev/mapper/3600508b40001417e0001c00001c90000
0 209715200 multipath 1 0 0 2 2 E 0 2 0 65:240 A 0 8:176 A 0 E 0 2 0 8:16 A
0 65:80 A 0
/sbin/dmsetup status /dev/mapper/3600508b40001417e0001c00001b60000
0 209715200 multipath 1 0 0 2 2 E 0 2 0 65:224 A 0 8:160 A 0 E 0 2 0 8:0 A 0
65:64 A 0
lvm version report
lvm version
LVM version: 2.00.24 (2004-09-16)
Library version: 1.00.19-ioctl (2004-07-03)
Driver version: 4.3.0
Guy
--
Dr. Guy Coates, Informatics System Group
The Wellcome Trust Sanger Institute, Hinxton, Cambridge, CB10 1SA, UK
Tel: +44 (0)1223 834244 ex 7199
http://www.patni.com
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