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I am trying to use multipath for the first time. And even that I have read the documentation both here at Ubuntu and on Redhat, I'm not coming closer to a solution.

I have 4 disks

  • /dev/sdb
  • /dev/sdc
  • /dev/sdd
  • /dev/sde

What I'm trying to setup is this

mpatha    
    /dev/sdb
    /dev/sdc

mpathb
    /dev/sdb
    /dev/sdc

But for now I get this

sdb  259:0        0  1.1T  0 disk
ââmpatha 253:1    0  1.1T  0 mpath
sdc  259:1        0  1.1T  0 disk
ââmpathb 253:2    0  1.1T  0 mpath
sdd  259:2        0  1.1T  0 disk
ââmpathd 253:3    0  1.1T  0 mpath
sde  259:3        0  1.1T  0 disk

My config looks like this:

defaults {
    user_friendly_names     yes
    find_multipaths         no
    max_fds                 32
    uid_attribute           ID_WWN
    path_checker            directio
}

blacklist_exceptions {
  property "(ID_WWN|SCSI_IDENT_.*|ID_SERIAL|DEVTYPE)"
  devnode "sd*"

But how to specify which drives goes to which MultiPath groups?

zx485
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Henning
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  • Are those really 4 disks or rather 2 disks connected over 2 paths? You cannot group different disks with multipath, only disks that have more than one path/connection. – Thomas Jun 10 '18 at 15:56
  • Hi Thomas, yes this is two disk over 2 paths. How can it see it is the samme disk but over different paths? – Henning Jun 10 '18 at 16:26
  • To check the device, look at the serial numbers or WWNs of the disks with `lsscsi -w`. For the multipath configuration, start with a simple default configuration which you can find at */usr/share/doc/device-mapper-multipath/multipath.conf* and set your own blacklist, which excludes all `sd*` devices. Then build up your rules on a running configuration. – Thomas Jun 10 '18 at 17:42
  • Thanks Thomas The clue was that disk should have the same WWN and the way I had setup the 2. path gave another WWN so when this was fixed it worked. Thanks to point that out. – Henning Jun 10 '18 at 19:26

0 Answers0