8.0-RELEASE: disk IO temporarily hangs up (ZFS or ATA related
problem)
Alexander Zagrebin
alexz at visp.ru
Wed Dec 16 08:59:34 UTC 2009
Hi!
I use onboard ICH7 SATA controller with two disks attached:
atapci1: <Intel ICH7 SATA300 controller> port
0x30c8-0x30cf,0x30ec-0x30ef,0x30c0-0x30c7,0x30e8-0x30eb,0x30a0-0x30af irq 19
at device 31.2 on pci0
atapci1: [ITHREAD]
ata2: <ATA channel 0> on atapci1
ata2: [ITHREAD]
ata3: <ATA channel 1> on atapci1
ata3: [ITHREAD]
ad4: 1430799MB <Seagate ST31500541AS CC34> at ata2-master SATA150
ad6: 1430799MB <WDC WD15EADS-00P8B0 01.00A01> at ata3-master SATA150
The disks are used for mirrored ZFS pool.
I have noticed that the system periodically locks up on disk operations.
After approx. 10 min of very slow disk i/o (several KB/s) the speed of disk
operations restores to normal.
gstat has shown that the problem is in ad6.
For example, there is a filtered output of iostat -x 1:
extended device statistics
device r/s w/s kr/s kw/s wait svc_t %b
ad6 818.6 0.0 10840.2 0.0 0 0.4 34
ad6 300.6 642.0 3518.5 24830.3 50 24.8 72
ad6 1.0 639.3 63.7 17118.3 0 62.1 98
ad6 404.5 4.0 6837.7 4.0 0 0.5 18
ad6 504.5 0.0 13667.2 0.0 1 0.7 32
ad6 633.3 0.0 13190.3 0.0 1 0.7 38
ad6 416.3 384.5 8134.7 24606.2 0 16.3 57
ad6 538.9 76.7 9772.8 2982.2 55 2.9 40
ad6 31.9 929.5 801.0 37498.6 0 27.2 82
ad6 635.5 0.0 13087.1 0.0 1 0.6 35
ad6 579.6 0.0 16669.8 0.0 0 0.8 43
ad6 603.6 0.0 11697.4 0.0 1 0.7 40
ad6 538.0 0.0 10438.7 0.0 0 0.9 47
ad6 30.9 898.4 868.6 40585.4 0 36.6 78
ad6 653.3 86.6 8566.6 202.7 1 0.8 40
ad6 737.1 0.0 6429.4 0.0 1 0.6 42
ad6 717.1 0.0 3958.7 0.0 0 0.5 36
ad6 1179.5 0.0 2058.9 0.0 0 0.1 15
ad6 1191.2 0.0 1079.6 0.0 1 0.1 15
ad6 985.1 0.0 5093.9 0.0 0 0.2 23
ad6 761.8 0.0 9801.3 0.0 1 0.4 31
ad6 698.7 0.0 9215.1 0.0 0 0.4 30
ad6 434.2 513.9 5903.1 13658.3 48 10.2 55
ad6 3.0 762.8 191.2 28732.3 0 57.6 99
ad6 10.0 4.0 163.9 4.0 1 1.6 2
Before this line we have a normal operations.
Then the behaviour of ad6 changes (pay attention to high average access time
and percent of "busy" significantly greater than 100):
ad6 0.0 0.0 0.0 0.0 1 0.0 0
ad6 1.0 0.0 0.5 0.0 1 1798.3 179
ad6 1.0 0.0 1.5 0.0 1 1775.4 177
ad6 0.0 0.0 0.0 0.0 1 0.0 0
ad6 10.0 0.0 75.2 0.0 1 180.3 180
ad6 0.0 0.0 0.0 0.0 1 0.0 0
ad6 83.7 0.0 862.9 0.0 1 21.4 179
ad6 0.0 0.0 0.0 0.0 1 0.0 0
ad6 1.0 0.0 63.7 0.0 1 1707.4 170
ad6 1.0 0.0 9.0 0.0 0 1791.0 178
ad6 10.9 0.0 172.2 0.0 2 0.2 0
ad6 24.9 0.0 553.7 0.0 1 143.3 179
ad6 0.0 0.0 0.0 0.0 7 0.0 0
ad6 2.0 23.9 32.4 1529.9 1 336.3 177
ad6 0.0 0.0 0.0 0.0 1 0.0 0
ad6 68.7 0.0 1322.8 0.0 1 26.3 181
ad6 0.0 0.0 0.0 0.0 1 0.0 0
ad6 27.9 0.0 193.7 0.0 1 61.6 172
ad6 1.0 0.0 2.5 0.0 1 1777.4 177
ad6 0.0 0.0 0.0 0.0 1 0.0 0
ad6 1.0 0.0 2.0 0.0 1 1786.9 178
ad6 0.0 0.0 0.0 0.0 1 0.0 0
ad6 2.0 0.0 6.5 0.0 1 899.4 179
ad6 0.0 0.0 0.0 0.0 1 0.0 0
ad6 1.0 0.0 2.0 0.0 1 1786.7 178
ad6 0.0 0.0 0.0 0.0 1 0.0 0
And so on for about 10 minutes.
Then the disk i/o is reverted to normal:
ad6 139.4 0.0 8860.5 0.0 1 4.4 61
ad6 167.3 0.0 10528.7 0.0 1 3.3 55
ad6 60.8 411.5 3707.6 8574.8 1 19.6 87
ad6 163.4 0.0 10334.9 0.0 1 4.4 72
ad6 157.4 0.0 9770.7 0.0 1 5.0 78
ad6 108.5 0.0 6886.8 0.0 0 3.9 43
ad6 101.6 0.0 6381.4 0.0 0 2.6 27
ad6 109.6 0.0 7013.9 0.0 0 2.0 22
ad6 121.4 0.0 7769.7 0.0 0 2.4 29
ad6 92.5 0.0 5922.6 0.0 1 3.4 31
ad6 122.4 19.9 7833.0 1273.7 0 3.9 54
ad6 83.6 0.0 5349.5 0.0 0 3.9 33
ad6 5.0 0.0 318.4 0.0 0 8.1 4
There are no ata error messages neither in the system log, nor on the
console.
The manufacture's diagnostic test is passed on ad6 without any errors.
The ad6 also contains swap partition.
I have tried to run several (10..20) instances of dd, which read and write
data
from and to the swap partition simultaneously, but it has not called the
lockup.
So there is a probability that this problem is ZFS related.
I have been forced to switch ad6 to the offline state... :(
Any suggestions on this problem?
--
Alexander Zagrebin
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