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[dm-devel] Problem using dm-multipath on first of 2 LUNs on system



I am attempting to implement dm-multipath on a RHEL4U6 server and I have been successful in enabling it on the second of 2 LUNs on the server but for whatever reason it will not create the device special files in /dev/mapper for the fist LUN.  `multipath –d` shows that it identifies the first LUN and wants to create the mpath0 files:

 

[root svwdcvispay01 etc]# multipath -d

create: mpath0 (36005076801810085c800000000000194)

[size=12 GB][features="1 queue_if_no_path"][hwhandler="0"]

\_ round-robin 0 [prio=50]

 \_ 1:0:0:0 sda 8:0  [ready]

\_ round-robin 0 [prio=10]

 \_ 1:0:1:0 sdc 8:32 [ready]

 

switchpg: mpath1 (36005076801810085c8000000000001a2)

[size=50 GB][features="1 queue_if_no_path"][hwhandler="0"]

\_ round-robin 0 [prio=50]

 \_ 1:0:1:1 sdd 8:48 [active][ready]

\_ round-robin 0 [prio=10]

 \_ 1:0:0:1 sdb 8:16 [active][ready]

 

[root svwdcvispay01 etc]#

 

 

However `multipath –v3` generates a “set ACT_CREATE: map does not exists” error in the mpath0 section:

 

[root svwdcvispay01 etc]# multipath -v3

load path identifiers cache

#

# all paths in cache :

#

36005076801810085c800000000000194  1:0:0:0 sda 8:0   IBM     /2145

36005076801810085c8000000000001a2  1:0:0:1 sdb 8:16 10 [active] IBM     /2145

36005076801810085c800000000000194  1:0:1:0 sdc 8:32   IBM     /2145

36005076801810085c8000000000001a2  1:0:1:1 sdd 8:48 50 [active] IBM     /2145

dm-0 blacklisted

dm-1 blacklisted

dm-2 blacklisted

dm-3 blacklisted

dm-4 blacklisted

md0 blacklisted

ram0 blacklisted

ram10 blacklisted

ram11 blacklisted

ram12 blacklisted

ram13 blacklisted

ram14 blacklisted

ram15 blacklisted

ram1 blacklisted

ram2 blacklisted

ram3 blacklisted

ram4 blacklisted

ram5 blacklisted

ram6 blacklisted

ram7 blacklisted

ram8 blacklisted

ram9 blacklisted

===== path info sda (mask 0x1f) =====

bus = 1

dev_t = 8:0

size = 25165824

vendor = IBM

product = 2145

rev = 0000

h:b:t:l = 1:0:0:0

tgt_node_name = 0x50050768010010b9

serial = 020060402172XX00

path checker = tur (controler setting)

state = 2

getprio = /sbin/mpath_prio_alua /dev/%n (controler setting)

prio = 50

uid = 36005076801810085c800000000000194 (cache)

===== path info sdb (mask 0x1f) =====

bus = 1

dev_t = 8:16

size = 104857600

vendor = IBM

product = 2145

rev = 0000

h:b:t:l = 1:0:0:1

tgt_node_name = 0x50050768010010b9

serial = 020060402172XX00

path checker = tur (controler setting)

state = 2

getprio = /sbin/mpath_prio_alua /dev/%n (controler setting)

prio = 10

uid = 36005076801810085c8000000000001a2 (cache)

===== path info sdc (mask 0x1f) =====

bus = 1

dev_t = 8:32

size = 25165824

vendor = IBM

product = 2145

rev = 0000

h:b:t:l = 1:0:1:0

tgt_node_name = 0x5005076801001082

serial = 020060402172XX00

path checker = tur (controler setting)

state = 2

getprio = /sbin/mpath_prio_alua /dev/%n (controler setting)

prio = 10

uid = 36005076801810085c800000000000194 (cache)

===== path info sdd (mask 0x1f) =====

bus = 1

dev_t = 8:48

size = 104857600

vendor = IBM

product = 2145

rev = 0000

h:b:t:l = 1:0:1:1

tgt_node_name = 0x5005076801001082

serial = 020060402172XX00

path checker = tur (controler setting)

state = 2

getprio = /sbin/mpath_prio_alua /dev/%n (controler setting)

prio = 50

uid = 36005076801810085c8000000000001a2 (cache)

#

# all paths :

#

36005076801810085c800000000000194  1:0:0:0 sda 8:0 50 [ready] IBM     /2145

36005076801810085c8000000000001a2  1:0:0:1 sdb 8:16 10 [active][ready] IBM

36005076801810085c800000000000194  1:0:1:0 sdc 8:32 10 [ready] IBM     /2145

36005076801810085c8000000000001a2  1:0:1:1 sdd 8:48 50 [active][ready] IBM

params = 1 queue_if_no_path 0 2 1 round-robin 0 1 1 8:48 1000 round-robin 0 1 1 8:16 1000

status = 1 0 0 2 1 A 0 1 0 8:48 A 0 E 0 1 0 8:16 A 0

Found matching wwid [36005076801810085c800000000000194] in bindings file.

Setting alias to mpath0

pgpolicy = group_by_prio (controler setting)

selector = round-robin 0 (internal default)

features = 1 queue_if_no_path (controler setting)

hwhandler = 0 (controler setting)

rr_weight = 1 (internal default)

rr_min_io = 1000 (config file default)

no_path_retry = NONE (internal default)

pg_timeout = NONE (internal default)

0 25165824 multipath 1 queue_if_no_path 0 2 1 round-robin 0 1 1 8:0 1000 round-robin 0 1 1 8:32 1000

set ACT_CREATE: map does not exists

Found matching wwid [36005076801810085c8000000000001a2] in bindings file.

Setting alias to mpath1

pgpolicy = group_by_prio (controler setting)

selector = round-robin 0 (internal default)

features = 1 queue_if_no_path (controler setting)

hwhandler = 0 (controler setting)

rr_weight = 1 (internal default)

rr_min_io = 1000 (config file default)

no_path_retry = NONE (internal default)

pg_timeout = NONE (internal default)

0 104857600 multipath 1 queue_if_no_path 0 2 1 round-robin 0 1 1 8:48 1000 round-robin 0 1 1 8:16 1000

set ACT_NOTHING: map unchanged

[root svwdcvispay01 etc]#

 

 

And notice that no /dev/mapper/mpath0 device special files were created:

 

[root svwdcvispay01 etc]# ls -la /dev/mapper

total 0

drwxr-xr-x  2 root root     160 Jan 29 09:53 .

drwxr-xr-x  9 root root    4900 Jan 29 09:51 ..

crw-------  1 root root  10, 63 Jan 21 16:15 control

brw-rw----  1 root disk 253,  0 Jan 21 16:15 mpath1

brw-rw----  1 root disk 253,  1 Jan 21 16:15 mpath1p1

brw-rw----  1 root disk 253,  2 Jan 21 16:15 mpath1p2

brw-rw----  1 root disk 253,  3 Jan 21 16:15 mpath1p3

brw-rw----  1 root disk 253,  4 Jan 21 16:15 mpath1p5

[root svwdcvispay01 etc]#

 

My /etc/multipath.conf file is basic but I have tried creating an alias entry that looks like “multipaths {multipath {wwid   36005076801810085c800000000000194 alias os}}” for the first LUN but the results are the same, it still won’t create any device special files for the first LUN.

 

[root svwdcvispay01 mapper]# cat /etc/multipath.conf | grep -v "#"

 

defaults {

        user_friendly_names yes

}

 

[root svwdcvispay01 mapper]#

 

I have been working this issue for over a week with IBM and RedHat tech support and they have been unhelpful.  I need to get this functional because the server in question has been unstable using a single path to the SAN due to stability issues we have had periodically with one of the SAN Volume Controllers.  If additional information is needed to troubleshoot this please let me know.

 

Joe little

littlej ae com

 


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