[Bug 1057054] Re: poor performance after upgrade to Precise

[Chris Weiss]

nothing.  from the 10.04 syslog, I do see this right after all the scsi
attach events:

Sep 24 13:54:01 file3 multipathd: sdm: add path (uevent)
Sep 24 13:54:02 file3 kernel: [    7.297268] sd 10:0:0:0: rdac: LUN 0 (unowned)
Sep 24 13:54:02 file3 kernel: [    7.299115] sd 8:0:0:0: rdac: LUN 0 (owned)
Sep 24 13:54:02 file3 kernel: [    7.300844] sd 9:0:0:0: rdac: LUN 0 (owned)
Sep 24 13:54:02 file3 kernel: [    7.302519] sd 10:0:0:1: rdac: LUN 1 (owned)
Sep 24 13:54:02 file3 kernel: [    7.304256] sd 10:0:0:2: rdac: LUN 2 (owned)
Sep 24 13:54:02 file3 kernel: [    7.306406] sd 10:0:0:3: rdac: LUN 3 (unowned)
Sep 24 13:54:02 file3 kernel: [    7.308048] sd 8:0:0:1: rdac: LUN 1 (unowned)
Sep 24 13:54:02 file3 kernel: [    7.309676] sd 9:0:0:1: rdac: LUN 1 (unowned)
Sep 24 13:54:02 file3 kernel: [    7.311221] sd 9:0:0:2: rdac: LUN 2 (unowned)
Sep 24 13:54:02 file3 kernel: [    7.313092] sd 8:0:0:2: rdac: LUN 2 (unowned)
Sep 24 13:54:02 file3 kernel: [    7.314769] sd 9:0:0:3: rdac: LUN 3 (owned)
Sep 24 13:54:02 file3 kernel: [    7.316383] sd 8:0:0:3: rdac: LUN 3 (owned)
Sep 24 13:54:02 file3 kernel: [    7.316388] rdac: device handler registered

and similar with the first 12.04 boot, except the "owned/unowned" lines
are intermixed with the scsi attaches instead of all at the end, so
that's different.

as far as active/active, I am seeing 140MB/s writes, so RR is working
well enough.  I think the MD3000 processor is the bottleneck. it's not
renowned for being super fast.  I did try adjusting the rr_weight and
rr_min_io, but it doens't seems to have changed much.  Defaults are
working well.  I'm not running Jumbo frames yet, so maybe that'll help
some.

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https://bugs.launchpad.net/bugs/1057054

Title:
  poor performance after upgrade to Precise

Status in “multipath-tools” package in Ubuntu:
  Invalid

Bug description:
  I had a Lucid x64 server working with a Dell MD3000i with 4 paths and
  worked as expected.  I added the "prio rdac" line to the conf file,
  then upgraded to Precise, and removed the old mpath_rdac line and
  reboot one more time, just to be sure.  I did this based on a section
  in https://help.ubuntu.com/12.04/serverguide/serverguide.pdf

  as a "sanity check" test, I'm doing 'pv < /dev/mapper/dellsas1 >
  /dev/null' (friendly names enabled).  On Lucid i'd get about 100MB/s
  After upgrading to Precise I get an almost solid 768kB/s.  If I
  instead use the 4 underlying /dev/sd* devices, 2 give errors as
  expected, and 2 run at about 100MB/s as expected so iscsi seems to be
  working correctly and multipath not.

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