# huge strange io activity for no reason on raidz



## nimmen (Mar 20, 2009)

hello, i have a problem with io activity
here is info:

7.1-STABLE FreeBSD 7.1-STABLE #5

root@[gw]:: zpool status
  pool: pool
 state: ONLINE
 scrub: scrub completed with 0 errors on Thu Mar 19 16:52:19 2009
config:

        NAME        STATE     READ WRITE CKSUM
        pool        ONLINE       0     0     0
          raidz1    ONLINE       0     0     0
            ad4     ONLINE       0     0     0
            ad8     ONLINE       0     0     0
            ad10    ONLINE       0     0     0
            ad12    ONLINE       0     0     0

errors: No known data errors

root@[gw]:: zpool iostat
               capacity     operations    bandwidth
pool         used  avail   read  write   read  write
----------  -----  -----  -----  -----  -----  -----
pool        1.31T  2.32T     33     14  3.88M   555K


top shows:
95.46% [irq20: atapci1]

CPU: 1.0% user,  0.0% nice,  6.2% system, 44.1% interrupt, 48.7% idle

root@[gw]:: iostat -xdw 1
                        extended device statistics
device     r/s   w/s    kr/s    kw/s wait svc_t  %b
ad4       29.8   9.6  1311.3   187.1    0  23.3   4
ad8       29.9   9.1  1311.4   187.1    0  35.4   5
ad10      29.8   9.5  1319.7   186.9    0  24.3   4
ad12      29.7  10.4  1315.4   184.4    0  35.0   6
                        extended device statistics
device     r/s   w/s    kr/s    kw/s wait svc_t  %b

ad4        0.0   0.0     0.0     0.0    0   0.0   0
ad8        0.0   0.0     0.0     0.0    0   0.0   0
ad10       0.0   0.0     0.0     0.0    0   0.0   0
ad12       0.0   0.0     0.0     0.0    0   0.0   0

gstat shows:

    0      0      0      0    0.0      0      0    0.0    0.0| ad4
    0      0      0      0    0.0      0      0    0.0    0.0| ad8
    0      0      0      0    0.0      0      0    0.0    0.0| ad10
    0      0      0      0    0.0      0      0    0.0    0.0| ad12

atapci1: <nVidia nForce MCP55 SATA300 controller> port 0x9f0-0x9f7,0xbf0-0xbf3,0x970-0x977,0xb70-0xb73,0xdc00-0xdc0f mem 0xfe02d000-0xfe02dfff irq 20 at device 5.0 on pci0
atapci1: [ITHREAD]
ata2: <ATA channel 0> on atapci1
ata3: <ATA channel 1> on atapci1

ATA channel 2:
    Master:  ad4 <Hitachi HDT721010SLA360/ST6OA31B> Serial ATA II
    Slave:       no device present
ATA channel 3:
    Master:      no device present
    Slave:       no device present

that is quite strange.
i have no idea why iostat first time shows huge activity and all next reports (using -w) shows zero activity, and actually it is zero activity, im 100% sure that there is nothing going on (no reads or writes), but zpool iostat shows activity too. gstat shows correct things, but top -S shows huge load on atapci1 and interrupts.

some loader.conf info:

vm.kmem_size="512M"
vm.kmem_size_max="1024M"
vfs.zfs.arc_max="256M"
kern.maxfiles="25600"
kern.maxfilesperproc="25600"

i had to change maxfiles because i ran out into limit few days ago. i have 2gb ram, it is home router, fileserver box.
CPU: AMD Athlon(tm) 64 X2 Dual Core Processor 4600+ (2411.13-MHz 686-class CPU)


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## jb_fvwm2 (Mar 20, 2009)

can you install /sysutils/pstree ?


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## nimmen (Mar 20, 2009)

i dont think that this will help (i think problem is in kernel or zfs or hardware(might be but im quite sure it is not)), output:

   31 root     -64    -     0K     8K WAIT   0  35.6H 90.38% [irq20: atapci1]

(pid =31)

root@[gw]:: pstree 31
--- 00031 root [irq20: atapci1]
root@[gw]:: pstree -p 31
root@[gw]::


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## Carpetsmoker (Mar 20, 2009)

This looks like a nForce4 chipset, those are pretty buggy, which may or may not have something to do with your problem.

Did you try rebooting the machine?


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## nimmen (Mar 20, 2009)

yes it is nforce4 chipset,
i will try rebooting some time later, but i thought maybe this problem would help improve nforce4 driver or some other issues related to this problem in freebsd 
that problem does not affect me for now it would suffice even 1/20 of the CPU i have for my current needs, but 1 core is very busy other is idle, just strange io activity, i have this server for almost a year and saw this problem after doing zpool scrub.


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