topic Re: identify the passive and active path in multipath in Operating System - Linux

identify the passive and active path in multipath

skt_skt — Mon, 22 Sep 2008 12:28:10 GMT

Red Hat Enterprise Linux AS release 4 (Nahant Update 6)

Linux hostname 2.6.9-67.ELsmp #1 SMP Wed Nov 7 13:58:04 EST 2007 i686 i686 i386 GNU/Linux

device-mapper-multipath-0.4.5-27.RHEL4
device-mapper-1.02.21-1.el4
lvm2-2.02.27-2.el4

How can i identify the passive and active path in multipath configiration.(No power path)

Re: identify the passive and active path in multipath

Ivan Ferreira — Mon, 22 Sep 2008 12:34:36 GMT

Just use the "multipath -l" command and depending of your configuration, you may have active/active paths.

Re: identify the passive and active path in multipath

skt_skt — Mon, 22 Sep 2008 12:37:50 GMT

# multipath -l
mpath0 (360060160f1731100e8ef486b8825dd11)
[size=89 GB][features="1 queue_if_no_path"][hwhandler="1 emc"]
\_ round-robin 0 [active]
\_ 3:0:1:0 sdc 8:32 [active]
\_ round-robin 0 [enabled]
\_ 3:0:0:0 sdb 8:16 [active]

Does this indicate both ar active?

Re: identify the passive and active path in multipath

skt_skt — Mon, 22 Sep 2008 12:53:18 GMT

i am trying to identify why i get these messages continuously(still coming)

Sep 22 15:20:52 hostname kernel: Device sdb not ready.
Sep 22 15:20:52 hostname kernel: end_request: I/O error, dev sdb, sector 0
Sep 22 15:20:52 hostname kernel: Buffer I/O error on device sdb, logical block 0

sdc is primary and sdb is passive( what i understood) not sure what is trying to access the passive path and why?

[root@shdbl3d ~]# lsof /dev/sdc
COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
multipath 3432 root 5r BLK 8,32 1849 /dev/sdc
[root@shdbl3d ~]# lsof /dev/sdb
COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
multipath 3432 root 4r BLK 8,16 1805 /dev/sdb

# multipath -v 3
load path identifiers cache
#
# all paths in cache :
#
360060160f1731100e8ef486b8825dd11 3:0:0:0 sdb 8:16 [active] DGC /RAID 5
360060160f1731100e8ef486b8825dd11 3:0:1:0 sdc 8:32 1 [active] DGC /RAID 5
hdc blacklisted
sda blacklisted

also what is meant by blacklisted above?

Re: identify the passive and active path in multipath

Court Campbell — Mon, 22 Sep 2008 12:57:20 GMT

The blacklisted devices are ones that you don;t want dm-mutilpath to handle. Like your local disk and cdrom.

Re: identify the passive and active path in multipath

Ivan Ferreira — Mon, 22 Sep 2008 13:39:35 GMT

Â¿Is this a storage with active/active controller?

Re: identify the passive and active path in multipath

skt_skt — Mon, 22 Sep 2008 13:46:34 GMT

it is emc_clariion .

Re: identify the passive and active path in multipath

Ivan Ferreira — Mon, 22 Sep 2008 14:02:08 GMT

Check if you don't have an incorrect definition for raw devices mapping in /etc/sysconfig/rawdevices, check also the output of:

raw -qa

Check also monitoring tools, like "smartd".

Re: identify the passive and active path in multipath

skt_skt — Mon, 22 Sep 2008 14:28:14 GMT

i dont have anything defined in /etc/sysconfig/rawdevices and "raw -qa" returns nothing

Re: identify the passive and active path in multipath

Court Campbell — Tue, 23 Sep 2008 02:01:02 GMT

I am kind of surprised that you are not seeing four paths to the disk. Can you post your multipath.conf file and the model of emc you have?

Re: identify the passive and active path in multipath

skt_skt — Tue, 23 Sep 2008 11:37:57 GMT

here is the diff with thr org file

# diff /etc/multipath.conf.orig /etc/multipath.conf
11c11
< devnode "*"
---
> devnode "^(sda|hdc)"

Re: identify the passive and active path in multipath

skt_skt — Tue, 23 Sep 2008 11:46:23 GMT

is it possible to diaable a path of a DM device in LVM ?how?

Re: identify the passive and active path in multipath

skt_skt — Tue, 23 Sep 2008 12:13:53 GMT

yes, i got the info about the lvm filter

[root@shdbl3d lvm]# diff lvm.conf.orig lvm.conf
52c52
< filter = [ "a/.*/" ]
---
> filter = [ "r|/dev/cdrom|", "r|/dev/hdc|", "r|/dev/sd[bc]|", "r|/dev/disk/by-path/.*|", "a/.*/" ]

Re: identify the passive and active path in multipath

skt_skt — Tue, 23 Sep 2008 13:02:13 GMT

I have onlt one HBA connected to the two different SPs and hance only two paths