Re: Problem using dm-multipath on first of 2 LUNs on system

"Gerald Nowitzky" <Nowitzky@xxxxxxx> · Tue, 29 Jan 2008 17:58:48 +0100

try and remove dm-0 to dm-4 from the blacklist. The 
devices in /dev/mapper are links to /dev/dm-x
(Gerald)

  ----- Original Message ----- 
  From: 
  LittleJ@xxxxxx 
  To: dm-devel@xxxxxxxxxx 
  Sent: Tuesday, January 29, 2008 4:42 
  PM
  Subject:  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@xxxxxx

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