[dm-devel] 4.4-rc4 multipath not working?

[Mike Snitzer]

On Mon, Dec 14 2015 at 11:55am -0500,
E V <eliventer at gmail.com> wrote:

> On Fri, Dec 11, 2015 at 4:00 PM, Mike Snitzer <snitzer at redhat.com> wrote:
> > On Fri, Dec 11 2015 at 12:23pm -0500,
> > E V <eliventer at gmail.com> wrote:
> >
> >> Just tried booting 4.4-rc4 on a system with using the mptsas driver:
> >> LSISAS3008: FWVersion(03.00.08.00), ChipRevision(0x02), BiosVersion(05.07.02.00)
> >>
> >> And multipath doesn't seem to be working, dmesg has lots of these:
> >>
> >> device-mapper: table: 254:2: multipath: unknown path selector type
> >> device-mapper: ioctl: error adding target to table
> >
> > You compile the path selector module you're attempting to use?
> Yes as far as I can tell, here are the _DM_ config options in my config:
> CONFIG_BLK_DEV_DM_BUILTIN=y
> # CONFIG_DM_MQ_DEFAULT is not set
> # CONFIG_DM_DEBUG is not set
> # CONFIG_DM_CRYPT is not set
> # CONFIG_DM_SNAPSHOT is not set
> # CONFIG_DM_THIN_PROVISIONING is not set
> # CONFIG_DM_CACHE is not set
> # CONFIG_DM_ERA is not set
> # CONFIG_DM_MIRROR is not set
> CONFIG_DM_RAID=m
> # CONFIG_DM_ZERO is not set
> CONFIG_DM_MULTIPATH=y
> CONFIG_DM_MULTIPATH_QL=y
> # CONFIG_DM_MULTIPATH_ST is not set
> # CONFIG_DM_DELAY is not set
> CONFIG_DM_UEVENT=y
> # CONFIG_DM_FLAKEY is not set
> # CONFIG_DM_VERITY is not set
> # CONFIG_DM_SWITCH is not set
> # CONFIG_DM_LOG_WRITES is not set
> 
> 
> >> Is it expected to work? and any suggestions on getting it to work,
> >
> > Yes, no reason dm-multipath shouldn't work (other than user error).
> Entirely possible, this is my first multipath setup.
> 
> > Figure out what the multipath table load line that failed to load
> > (verbose logging with multipathd?) and make sure you have the
> > corresponding path selector modules enabled in your .config
> 
> Running multipathd with -v3 shows this in it's output, trimming 1st
> few columns for the 1st mpath device in the output. Doesn't mean much
> to me, other then I see the queue_length selector is set as expected:
> read /etc/multipath.conf
> multipath.conf line 8, duplicate keyword: defaults
> loading /lib/multipath/libcheckdirectio.so checker
> loading /lib/multipath/libprioconst.so prioritizer
> set open fds limit to 1048576/1048576
> sdab: ownership set to mpathc
> sdab: not found in pathvec
> sdab: mask = 0xc
> sdab: path state = running
> sdab: get_state
> directio: starting new request
> directio: io finished 4096/0
> sdab: state = up
> sdab: const prio = 1
> mpathc: pgfailback = -1 (config file default)
> mpathc: pgpolicy = failover (internal default)
> mpathc: selector = queue_length (config file default)
> mpathc: features = 0 (config file default)
> mpathc: hwhandler = 0 (internal default)
> mpathc: rr_weight = 1 (internal default)
> mpathc: minio = 1 rq (config file default)
> mpathc: no_path_retry = 0 (internal default)
> mpathc: fast_io_fail_tmo = 5 (config file default)
> mpathc: retain_attached_hw_handler = 1 (config file default)
> sdd: No SAS end device for 'end_device-1:0'
> sdab: No SAS end device for 'end_device-1:1'
> mpathc: remove queue_if_no_path from '0'
> mpathc: assembled map [0 0 2 1 queue_length 1 1 8:48 1 queue_length 1 1 65:176 1]

This table looks malformed.

Expected format is (from drivers/md/dm-mpath.c):

/*-----------------------------------------------------------------
 * Constructor/argument parsing:
 * <#multipath feature args> [<arg>]*
 * <#hw_handler args> [hw_handler [<arg>]*]
 * <#priority groups>
 * <initial priority group>
 *     [<selector> <#selector args> [<arg>]*
 *      <#paths> <#per-path selector args>
 *         [<path> [<arg>]* ]+ ]+
 *---------------------------------------------------------------*/

So in your case, breaking the map into logical sections, it is:

0 0 2 1

  <#multipath feature args> = 0 
  <#hw_handler args> = 0
  <#priority groups> = 2
  <initial priority group> = 1

queue_length 1 1 8:48 1

     <selector> = queue_length
     <#selector args> = 1 <BUT NO SELECTOR ARG!?>
     <#paths> = 1 <path> = 8:48 <arg> = 1

queue_length 1 1 65:176 1

     <selector> = queue_length <#selector args> = 1 <BUT NO SELECTOR ARG!?>
     <#paths> = 1 <path> = 65:176 <arg> = 1

What do you have in your multipath.conf for 'path_selector'?

AFAIK, it should be: path_selector queue-length 0

(cc'ing Ben in case you need more multipath.conf help)