DM Multipath Configuration on Linux
unique scsi identifiers
list all scsi devices
[root@devdb ~]# cat /proc/partitions
major minor #blocks name
8 0 291991552 sda
8 1 204800 sda1
8 2 512000 sda2
8 3 20971520 sda3
8 4 270301184 sda4
8 16 5242880 sdb
8 64 104857600 sde
8 32 104857600 sdc
8 80 104857600 sdf
8 112 104857600 sdh
8 48 104857600 sdd
8 128 157286400 sdi
8 144 209715200 sdj
8 160 419430400 sdk
8 96 104857600 sdg
8 176 5242880 sdl
8 208 104857600 sdn
8 224 104857600 sdo
8 240 104857600 sdp
8 192 104857600 sdm
65 0 104857600 sdq
65 16 104857600 sdr
65 32 157286400 sds
65 48 209715200 sdt
65 64 419430400 sdu
252 0 33554432 dm-0
252 1 5242880 dm-1
252 2 104857600 dm-2
252 3 104857600 dm-3
252 4 104857600 dm-4
252 5 104857600 dm-5
252 6 104857600 dm-6
252 7 157286400 dm-7
252 8 209715200 dm-8
252 9 419430400 dm-9
252 10 104857600 dm-10
252 11 1 dm-11
252 12 209712447 dm-12
252 13 122880000 dm-13
obtain clusterware device unique scsi identifiers
[root@devdb ~]# for i in `ls /dev/sd[a-z]` ; do echo $i "`/sbin/scsi_id i --whitelisted --device=$i`"; done | sort -k2
/dev/sdc 36005076802810b121800000000000005
/dev/sdm 36005076802810b121800000000000005
/dev/sdd 36005076802810b121800000000000006
/dev/sdn 36005076802810b121800000000000006
/dev/sde 36005076802810b121800000000000007
/dev/sdo 36005076802810b121800000000000007
/dev/sdf 36005076802810b121800000000000008
/dev/sdp 36005076802810b121800000000000008
/dev/sdg 36005076802810b121800000000000009
/dev/sdq 36005076802810b121800000000000009
/dev/sdh 36005076802810b12180000000000000a
/dev/sdr 36005076802810b12180000000000000a
/dev/sdb 36005076802810b12180000000000000b
/dev/sdl 36005076802810b12180000000000000b
/dev/sdi 36005076802810b12180000000000000c
/dev/sds 36005076802810b12180000000000000c
/dev/sdj 36005076802810b12180000000000000e
/dev/sdt 36005076802810b12180000000000000e
/dev/sdk 36005076802810b12180000000000000f
/dev/sdu 36005076802810b12180000000000000f
/dev/sda 3600605b0061b8b301944b4a80d86a2f9
configure multipathing
enable the multipath configuration file and starts the multipathd daemon
[root@devdb ~]# mpathconf --enable --with_multipathd y
[root@devdb ~]# tree -f /etc/multipath*
/etc/multipath.conf
/etc/multipath
├── /etc/multipath/bindings
└── /etc/multipath/wwids
multipath.conf
[root@devdb ~]# cat /etc/multipath.conf
# This is a basic configuration file with some examples, for device mapper
# multipath.
# For a complete list of the default configuration values, see
# /usr/share/doc/device-mapper-multipath-0.4.9/multipath.conf.defaults
# For a list of configuration options with descriptions, see
# /usr/share/doc/device-mapper-multipath-0.4.9/multipath.conf.annotated
#
# REMEMBER: After updating multipath.conf, you must run
#
# service multipathd reload
#
# for the changes to take effect in multipathd
... ...
blacklist {
wwid 3600605b0061b8b301944b4a80d86a2f9
}
wwids
[root@devdb ~]# cat /etc/multipath/wwids
# Multipath wwids, Version : 1.0
# NOTE: This file is automatically maintained by multipath and multipathd.
# You should not need to edit this file in normal circumstances.
#
# Valid WWIDs:
/36005076802810b121800000000000005/
bindings
[root@devdb ~]# cat /etc/multipath/bindings
# Multipath bindings, Version : 1.0
# NOTE: this file is automatically maintained by the multipath program.
# You should not need to edit this file in normal circumstances.
#
# Format:
# alias wwid
#
mpatha 3600605b0061b8b301944b4a80d86a2f9
mpathb SIBM 2145 0200a042c486XX25
mpathc 36005076802810b121800000000000005
multipath -v3
[root@devdb ~]# multipath -v3
... ...
===== paths list =====
uuid hcil dev dev_t pri dm_st chk_st vend/prod
3600605b0061b8b301944b4a80d86a2f9 0:2:0:0 sda 8:0 1 undef ready IBM,Serve
36005076802810b121800000000000005 3:0:0:0 sdb 8:16 50 undef ready IBM,2145
36005076802810b121800000000000005 4:0:0:0 sdc 8:32 10 undef ready IBM,2145
... ...
alias
alias settings
[root@devdb ~] vim /etc/multipath.conf
... ...
defaults {
user_friendly_names yes
}
... ...
multipaths {
multipath {
wwid 36005076802810b121800000000000005
alias data
}
}
... ...
stop device mapping
[root@devdb ~] service multipathd stop
flush device mappings
[root@devdb ~] multipath -F
start device mapping
[root@devdb ~] service multipathd start
show multipath topology
[root@devdb ~]# multipath -ll
data (36005076802810b121800000000000005) dm-5 IBM,2145
size=400G features='0' hwhandler='0' wp=rw
|-+- policy='round-robin 0' prio=50 status=active
| `- 4:0:0:9 sdd 65:64 active ready running
`-+- policy='round-robin 0' prio=10 status=enabled
`- 3:0:0:9 sdc 8:160 active ready running
show created devices
[root@devdb ~]# dmsetup ls | sort
data (252:9)
erpdb_asm_crsdg (252:1)
erpdb_asm_dg_1 (252:3)
erpdb_asm_dg_2 (252:6)
erpdb_asm_dg_3 (252:2)
erpdb_asm_dg_4 (252:4)
erpdb_asm_dg_5 (252:10)
erpdb_asm_fradg (252:5)
erpdb_fs_arch_db1 (252:7)
patch (252:8)
patchp1 (252:11)
patchp5 (252:12)
vg_devdb-LV_DB (252:13)
vg_devdb-LV_SWAP (252:0)
adminstartion commands
mpathconf
[root@devdb ~]# mpathconf --help
usage: /sbin/mpathconf <command>
Commands:
Enable: --enable
Disable: --disable
Set user_friendly_names (Default n): --user_friendly_names <y|n>
Set find_multipaths (Default n): --find_multipaths <y|n>
Load the dm-multipath modules on enable (Default y): --with_module <y|n>
start/stop/reload multipathd (Default n): --with_multipathd <y|n>
chkconfig on/off multipathd (Default y): --with_chkconfig <y|n>
multipath
[root@dev1 etc]# multipath -l
multipath-tools v0.4.9 (04/04, 2009)
Usage:
multipath [-c] [-d] [-r] [-v lvl] [-p pol] [-b fil] [-q] [dev]
multipath -l|-ll|-f [-v lvl] [-b fil] [dev]
multipath -F [-v lvl]
multipath -h
Where:
-h print this usage text
-l show multipath topology (sysfs and DM info)
-ll show multipath topology (maximum info)
-f flush a multipath device map
-F flush all multipath device maps
-c check if a device should be a path in a multipath device
-q allow queue_if_no_path when multipathd is not running
-d dry run, do not create or update devmaps
-r force devmap reload
-p policy failover|multibus|group_by_serial|group_by_prio
-b fil bindings file location
-p pol force all maps to specified path grouping policy :
. failover one path per priority group
. multibus all paths in one priority group
. group_by_serial one priority group per serial
. group_by_prio one priority group per priority lvl
. group_by_node_name one priority group per target node
-v lvl verbosity level
. 0 no output
. 1 print created devmap names only
. 2 default verbosity
. 3 print debug information
dev action limited to:
. multipath named 'dev' (ex: mpath0) or
. multipath whose wwid is 'dev' (ex: 60051..)
. multipath including the path named 'dev' (ex: /dev/sda)
. multipath including the path with maj:min 'dev' (ex: 8:0)
multipathd
[root@devdb ~]# multipathd -k
multipathd> help
multipath-tools v0.4.9 (04/04, 2009)
CLI commands reference:
list|show paths
list|show paths format $format
list|show status
list|show daemon
list|show maps|multipaths
list|show maps|multipaths status
list|show maps|multipaths stats
list|show maps|multipaths format $format
list|show maps|multipaths topology
list|show topology
list|show map|multipath $map topology
list|show config
list|show blacklist
list|show devices
list|show wildcards
add path $path
remove|del path $path
add map|multipath $map
remove|del map|multipath $map
switch|switchgroup map|multipath $map group $group
reconfigure
suspend map|multipath $map
resume map|multipath $map
resize map|multipath $map
disablequeueing map|multipath $map
restorequeueing map|multipath $map
disablequeueing maps|multipaths
restorequeueing maps|multipaths
reinstate path $path
fail path $path
paths count
forcequeueing daemon
restorequeueing daemon
quit|exit
map|multipath $map getprstatus
map|multipath $map setprstatus
map|multipath $map unsetprstatus
full configure
[root@devdb ~]# grep -v '^#' /etc/multipath.conf
defaults {
polling_interval 30
path_selector "round-robin 0"
path_grouping_policy multibus
path_checker readsector0
rr_min_io 100
max_fds 8192
rr_weight priorities
failback immediate
no_path_retry fail
user_friendly_names yes
}
blacklist {
wwid 3600605b0061b8b301944b4a80d86a2f9
devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"
devnode "^hd[a-z]"
}
devices {
device {
vendor "IBM"
product "2145"
path_grouping_policy group_by_prio
getuid_callout "/lib/udev/scsi_id --whitelisted --device=/dev/%n"
path_selector "round-robin 0"
path_checker tur
features "1 queue_if_no_path"
hardware_handler "0"
prio alua
failback immediate
rr_weight uniform
rr_min_io 1000
rr_min_io_rq 1
}
}
multipaths {
multipath {
wwid 36005076802810b121800000000000005
alias erpdb_asm_dg_1
}
multipath {
wwid 36005076802810b121800000000000006
alias erpdb_asm_dg_2
}
multipath {
wwid 36005076802810b121800000000000007
alias erpdb_asm_dg_3
}
multipath {
wwid 36005076802810b121800000000000008
alias erpdb_asm_dg_4
}
multipath {
wwid 36005076802810b121800000000000009
alias erpdb_asm_dg_5
}
multipath {
wwid 36005076802810b12180000000000000a
alias erpdb_asm_fradg
}
multipath {
wwid 36005076802810b12180000000000000b
alias erpdb_asm_crsdg
}
multipath {
wwid 36005076802810b12180000000000000c
alias erpdb_fs_arch_db1
}
multipath {
wwid 36005076802810b12180000000000000e
alias patch
}
multipath {
wwid 36005076802810b12180000000000000f
alias data
}
}
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