[Bug 899173] [NEW] iostat/kernel output for dm devices broken

[James Beal]

Public bug reported:

lsb_release -rd
Description:	Ubuntu 10.04.3 LTS
Release:	10.04

apt-cache policy sysstat
sysstat:
  Installed: 9.0.6-2
  Candidate: 9.0.6-2
  Version table:
 *** 9.0.6-2 0
        990 http://archive.ubuntu.com/ubuntu/ lucid/main Packages
        100 /var/lib/dpkg/status

 apt-cache policy linux
linux:
  Installed: (none)
  Candidate: 2.6.32.36.42
  Version table:
     2.6.32.36.42 0
        990 http://archive.ubuntu.com/ubuntu/ lucid-updates/main Packages
     2.6.32.35.41 0
        990 http://archive.ubuntu.com/ubuntu/ lucid-security/main Packages
     2.6.32.21.22 0
        990 http://archive.ubuntu.com/ubuntu/ lucid/main Packages


Firstly I have no /dev/dm* device files and I would expect to have them.

dmsetup ls
36000402002fc827b66970aae00000000	(251, 3)
36000402002fc827b66970aac00000000	(251, 2)
vg1-lvol0	(251, 0)
36000402002fc827b66970aaf00000000	(251, 1)
36000402002fc827b66970aad00000000	(251, 4)
ls -l /dev/dm*
ls: cannot access /dev/dm*: No such file or directory

This is the mapping of paths to /dev/sd
 multipath -ll
36000402002fc827b66970aae00000000dm-3 NEXSAN  ,SATABeast2    
[size=15T][features=1 queue_if_no_path][hwhandler=0]
\_ round-robin 0 [prio=130][active]
 \_ 0:0:0:2 sdc 8:32  [active][ready]
\_ round-robin 0 [prio=10][enabled]
 \_ 2:0:0:2 sdg 8:96  [active][ready]
36000402002fc827b66970aac00000000dm-2 NEXSAN  ,SATABeast2    
[size=15T][features=1 queue_if_no_path][hwhandler=0]
\_ round-robin 0 [prio=130][active]
 \_ 0:0:0:3 sdd 8:48  [active][ready]
\_ round-robin 0 [prio=10][enabled]
 \_ 2:0:0:3 sdh 8:112 [active][ready]
36000402002fc827b66970aaf00000000dm-1 NEXSAN  ,SATABeast2    
[size=15T][features=1 queue_if_no_path][hwhandler=0]
\_ round-robin 0 [prio=130][active]
 \_ 2:0:0:1 sdf 8:80  [active][ready]
\_ round-robin 0 [prio=10][enabled]
 \_ 0:0:0:1 sdb 8:16  [active][ready]
36000402002fc827b66970aad00000000dm-4 NEXSAN  ,SATABeast2    
[size=15T][features=1 queue_if_no_path][hwhandler=0]
\_ round-robin 0 [prio=130][active]
 \_ 2:0:0:4 sdi 8:128 [active][ready]
\_ round-robin 0 [prio=10][enabled]
 \_ 0:0:0:4 sde 8:64  [active][ready]

So looking at dm-4
iostat /dev/dm-4 /dev/sdi /dev/sde 10 2
Linux 2.6.38-11-server (sf-nfs-red-c02d) 	02/12/11 	_x86_64_	(8 CPU)

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.16    0.00    1.94    3.68    0.00   94.22

Device:            tps   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn
sde              59.85      8839.83      8050.23 19180626896 17467347187
dm-4              0.00         0.00         0.00       8704          0
sdi               0.00         0.00         0.00       8208          0

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.36    0.00    1.68    0.00    0.00   97.96

Device:            tps   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn
sde              15.40         0.00      6813.30          0      68133
dm-4              0.00         0.00         0.00          0          0
sdi               0.00         0.00         0.00          0          0

so dm-4 is not mirroring sde

Looking in /proc/diskstats doesn't look if dm devices are being updated

egrep  'sde|dm-4' /proc/diskstats 
   8      64 sde 90651080 89903468 19180626896 1410791480 39203730 114164693 17468206968 366306424 0 274360100 1777314394
 251       4 dm-4 986 102 8704 790 0 0 0 0 0 790 790
root at sf-nfs-red-c02d:/lib/udev/rules.d# egrep  'sde|dm-4' /proc/diskstats 
   8      64 sde 90651080 89903468 19180626896 1410791480 39203848 114165149 17468277323 366314084 0 274360470 1777322054
 251       4 dm-4 986 102 8704 790 0 0 0 0 0 790 790

** Affects: sysstat (Ubuntu)
     Importance: Undecided
         Status: New

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Title:
  iostat/kernel  output for dm devices broken

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