Description of problem:

The command vmstat shows the system i/o is intermittent when a command of "dd
if=/dev/zero of=/file bs=1024k count=100000" is running on a cciss disk.

Please look at the volume of â€bo“, you can find most of value is zero, It looks
like the IO was always blocked.

procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----

 r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy id wa

 0  5    176  14912  12224 1799968    0    0    27  6670  179    52  0  4 58 38

 0  5    176  17344  12576 1801680    0    0     0     0 4538   240  0  7 25 68

 1  2    176  13792  12752 1741648    0    0    84 734108 4451   176  0 21 31 47

 0  4    176  16096  12832 1737440    0    0     4 12480 4711   184  0  2 50 48

 0  4    176  18848  12832 1737440    0    0    32     0 4424    33  0  0 50 50

 0  4    176  21152  12848 1737424    0    0     0     4 4432   169  0  0 50 50

 0  3    176  26976  12848 1737424    0    0     0     0 4460    41  0  1 50 49

 0  3    176  29216  12848 1737424    0    0    80     0 4479   167  0  0 50 50

 0  3    176  32288  12848 1737424    0    0   112     0 4375    35  0  0 50 50

 0  3    176  35488  12848 1737424    0    0     0     0 4479   167  0  1 50 49

 0  3    176  38816  12848 1739488    0    0     8     0 4403    31  0  1 50 49

 0  3    176  41888  12848 1739488    0    0     0     0 4464   167  0  1 50 49

 0  3    176  45536  12848 1739488    0    0     0     0 4446    29  0  1 50 49

 0  2    176  47840  12848 1739488    0    0     0     0 4451   171  0  1 50 49

 0  2    176  50720  12848 1739488    0    0     0     0 4373    31  0  0 50 50

 0  2    176  53152  12848 1739488    0    0     0     0 4426   165  0  0 50 50

 0  2    176  56096  12848 1739488    0    0     0     0 4374    29  0  0 50 50

 0  2    176  58080  12848 1739488    0    0     0     0 4439   165  0  0 50 50

 0  2    176  61152  12848 1739488    0    0     0     0 4348    33  0  1 50 49

 0  2    176  64608  12848 1739488    0    0     0     0 4439   167  0  1 50 49

 0  2    176  67104  12848 1739488    0    0     0     0 4361    29  0  1 50 49

 0  2    176  70304  12848 1739488    0    0     0     0 4448   165  0  0 50 50

 0  2    176  72992  12848 1739488    0    0     0     0 4366    29  0  1 50 49

 0  2    176  75616  12848 1739488    0    0     0     0 4431   169  0  0 50 50

 1  3    176  77312  12960 1762080    0    0     8  4016 4320    31  0 15 56 29

 2  2    176  12224  13408 1829744    0    0    36 58512 4836   606  0 17 33 49

 0  5    176  12672  13328 1813312    0    0     4 193108 4550    97  0 14 25 61

 0  5    176  17408  13360 1813280    0    0    20     0 4583   225  0  9 25 66

 1  4    176  12032  13392 1821504    0    0     4     0 4473    62  0  3 23 74

 0  5    176  19904  13312 1817456    0    0     4     0 4565   222  0  7  0 93

 1  5    176  17312  13712 1817056    0    0    20 24372 4525   298  0 18 10 72

 0  4    176  17184  14400 1812240    0    0     8 42784 4649   451  0 13 40 48

 0  3    176  17184  14416 1812224    0    0    36 33828 4446   138  0  1 51 49

 0  6    176  16288  14640 1760400    0    0     0 647860 4705   622  0 22 23 55

 0  6    176  15136  14864 1764304    0    0     4     0 4484   407  0  5 25 70

 0  6    176  18144  14896 1764272    0    0     8     0 4562   241  0  1 25 74

 1  6    176  11744  15248 1776304    0    0     4     0 4476   515  0  7 25 68

 0  6    176  18080  15408 1772016    0    0     8     0 4542   785  0  3 25 72

 0  6    176  21856  15408 1772016    0    0    16     0 4478    78  0  1 25 74

 0  6    176  17376  15760 1779920    0    0    48     0 4566   564  0  8 25 67

 0  6    176  16160  15888 1783920    0    0     4     0 4459   428  0  3 25 72

 0  6    176  20064  15888 1783920    0    0    80     0 4551   208  0  1 25 74

 2  5    176  15072  15968 1792096    0    0    16     0 4458    78  0  2 25 73

 0  6    176  14176  16336 1791728    0    0     4     0 4546   443  0  9 25 66

 1  5    176  16800  16352 1793776    0    0    16     0 4456    80  0  2 25 73

 0  6    176  13536  14688 1801632    0    0     0     0 4498   530  0  6 25 69

 0  6    176  19168  14704 1799552    0    0     4     0 4442    97  0  2 25 73

 0  6    176  22048  14704 1799552    0    0    80     0 4471   207  0  0 25 75

 1  7    176  14304  14688 1783056    0    0    24 249076 4458   159  0 13 26 60

 0  3    176  13152  14448 1744080    0    0     4 500260 4601   226  0 15 30 55

 0  4    176  16928  14480 1739920    0    0     4  4112 4749    33  0  1 50 49

 0  4    176  20192  14480 1739920    0    0    32     0 4569   167  0  1 50 49

 0  4    176  22752  14496 1739904    0    0    16     4 4389    33  0  0 50 50

 0  3    176  25184  14496 1739904    0    0     0     0 4422   173  0  1 50 49

 0  3    176  27680  14496 1739904    0    0    16     0 4339    33  0  0 50 50

 0  3    176  29984  14496 1739904    0    0     0     0 4413   165  0  0 50 50

Version-Release number of selected component (if applicable):


How reproducible:

Always

Steps to Reproduce:
1. Find a mechine with HP SMART RAID CONTROLLER (any of P400, P600, E200)
2. Execute dd commands.
3. Run vmstat in another console and you can get the result.
  
Actual results:

But If we install the kernel of 2.6.9-59(RHEL4U6beta), the vmstat can report 
consecutive　I/O.

Expected results:


Additional info:

What the customer did:

Installed the kernel of RHEL4.4 RHEL4.5.

Update cciss driver to latest version on RHEL4.3

The question is:

Was the output of vmstat OK or not? 

Is it a issue on kernel, driver or hardware?

Any advice if we want to make further detail analysis.

Thanks