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3 replies Latest Post - ‏2010-08-25T12:39:41Z by Miguel_Sanders
Miguel_Sanders
Miguel_Sanders
4 Posts
ACCEPTED ANSWER

Pinned topic SLES 11 and Mulltipath

‏2010-08-23T17:18:49Z |
Hi folks

I'm currently experimenting with Linux on POWER and I have a question concerning the use of multipathing for the root partitions. A LUN is served via both VIO servers to the SLES VIO client, resulting in the following output of fdisk -l:

Disk /dev/sda: 53.7 GB, 53687091200 bytes
64 heads, 32 sectors/track, 51200 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Disk identifier: 0x3f360a00

Device Boot Start End Blocks Id System
/dev/sda1 * 1 1 397+ 41 PPC PReP Boot
Partition 1 does not end on cylinder boundary.
/dev/sda2 204 2260 2104515 82 Linux swap / Solaris
Partition 2 does not end on cylinder boundary.
/dev/sda3 2260 51200 50114767+ 83 Linux
Partition 3 does not end on cylinder boundary.

Disk /dev/sdb: 53.7 GB, 53687091200 bytes
64 heads, 32 sectors/track, 51200 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Disk identifier: 0x3f360a00

Device Boot Start End Blocks Id System
/dev/sdb1 * 1 1 397+ 41 PPC PReP Boot
Partition 1 does not end on cylinder boundary.
/dev/sdb2 204 2260 2104515 82 Linux swap / Solaris
Partition 2 does not end on cylinder boundary.
/dev/sdb3 2260 51200 50114767+ 83 Linux
Partition 3 does not end on cylinder boundary.
scsi_id shows the following for both disks:
#/lib/udev/scsi_id --whitelisted --replace-whitespace --device=/dev/sda
36005076304ffc5b80000000000000081
  1. /lib/udev/scsi_id --whitelisted --replace-whitespace --device=/dev/sdb
36005076304ffc5b80000000000000081

So they are the same disks.
The kernel module for multipathing (dm_multipath) is loaded and the multipathd daemon is running.

However, running multipath -d shows
create: 36005076304ffc5b80000000000000081 undef AIX,VDASD
size=50G features='0' hwhandler='0' wp=undef
`-+- policy='round-robin 0' prio=1 status=undef
|- 2:0:1:0 sda 8:0 undef ready running
`- 3:0:1:0 sdb 8:16 undef ready running

And dmesg is showing
device-mapper: table: 253:0: multipath: error getting device
device-mapper: ioctl: error adding target to table

Any idea what I am missing?

(Note that both fstab and lilo.conf are using "Device by ID" notation)
Updated on 2010-08-25T12:39:41Z at 2010-08-25T12:39:41Z by Miguel_Sanders
  • Brian_King
    Brian_King
    20 Posts
    ACCEPTED ANSWER

    Re: SLES 11 and Mulltipath

    ‏2010-08-23T17:41:17Z  in response to Miguel_Sanders
    Since are probably currently booted from /dev/sda or /dev/sdb, multipath can't create the multipath device since the device is already in use. If you are using SLES 11 SP1, when you do the install, there is an option in the advanced partitioning screen where you can enable multipath and install directly to a multipath device. If you've already installed SLES 11, you can follow the instructions on Novell's website to enable multipath to your root device:

    http://www.novell.com/documentation/sles10/stor_evms/?page=/documentation/sles10/stor_evms/data/mpioroot.html
  • Miguel_Sanders
    Miguel_Sanders
    4 Posts
    ACCEPTED ANSWER

    Re: SLES 11 and Mulltipath

    ‏2010-08-24T06:26:38Z  in response to Miguel_Sanders
    Many thanks.
  • Miguel_Sanders
    Miguel_Sanders
    4 Posts
    ACCEPTED ANSWER

    Re: SLES 11 and Mulltipath

    ‏2010-08-25T12:39:41Z  in response to Miguel_Sanders
    Hi

    Multipathing to both VIO servers is OK now. But is there also a procedure to add an additional LUN to 'mirror' the partitions?

    My setup consists of the following partitions:
    • /dev/dm-1 , PPC PReP Boot (ID 41)
    • /dev/dm-2 , Linux (ID 83) containing the boot partition
    • /dev/dm-3, Linux LVM (ID 8E) containing my 'rootvg'

    1. lvscan
    ACTIVE '/dev/rootvg/hd1' http://1.00 GB inherit
    ACTIVE '/dev/rootvg/hd10opt' http://512.00 MB inherit
    ACTIVE '/dev/rootvg/hd2' http://3.00 GB inherit
    ACTIVE '/dev/rootvg/hd3' http://2.00 GB inherit
    ACTIVE '/dev/rootvg/hd4' http://512.00 MB inherit
    ACTIVE '/dev/rootvg/hd6' http://20.00 GB inherit
    ACTIVE '/dev/rootvg/hd9var' http://512.00 MB inherit

    For /dev/dm-1, I assume this can only be mirrored using dd, right?
    What about /dev/dm-1 and /dev/dm-2, can I employ Linux RAID and if so, how? (Online?)

    Cheers

    Miguel