Re: iostat - multiblock read count

From: hopehope_123 <hopehope_123_at_yahoo.com>
Date: 25 May 2005 07:43:44 -0700
Message-ID: <1117032224.343383.297030@g14g2000cwa.googlegroups.com>

Hi Friends ,

Thank you very much for your replies , Fabrizio it is good to hear from you again , i have made your tests here , these are the results:

redhat linux advanced server ia64 , ocfs file system on emc raid10. + fibre channel , no asyc , but direct_io active

time dd if=/dev/zero of=/oracle/koccrm01/test bs=4096k count=100 100+0 records in
100+0 records out

real    0m5.964s
user    0m0.001s
sys     0m3.923s


Device:  rrqm/s   wrqm/s   r/s        w/s      rsec/s   wsec/s
avgrq-sz  avgqu-sz   await  svctm  %util
sdn       7699.00 7624.00  347.00  227.00 8046.00 7851.00     27.70
1.28          2.22   0.65  38.10

7851.00 wsec/s = 7851*(512/1024)=3925,5KBytes/sec. (1 sector=512k)

3925,5 / 227.00 = 17,29 kb.

2. same server: redhat linux advanced server ia64 , this time ext3 file system ,

for aio : /proc/sys/fs/aio_nr = 0 so it is not active.

time dd if=/dev/zero of=/oracle/stagetmp/tmp/test bs=4096k count=100 100+0 records in
100+0 records out

real    0m1.089s
user    0m0.002s
sys     0m1.071s

cant get iostat since it is too fast . tried by increasing the file size :

time dd if=/dev/zero of=/oracle/stagetmp/tmp/test bs=4096k count=1000

Device:  rrqm/s wrqm/s     r/s    w/s       rsec/s  wsec/s
avgrq-sz  avgqu-sz     await     svctm  %util
sdl1       0.00   20951.00  1.00  958.00    8.00   175048.00   182.54

4190621.19 379.70 1.02 100.00

87524 KB. / 958 = 91KB.

3. redhat linux x86 , ext3 file system , aio is same with above (not active)

time dd if=/dev/zero of=/oracle/tolga/test bs=4096k count=100 100+0 records in
100+0 records out

3.97s real 0.00s user 2.23s system

Device:  rrqm/s wrqm/s   r/s    w/s       rsec/s  wsec/s       avgrq-sz
 avgqu-sz   await      svctm  %util
sdb5       0.00 22098.00  0.00  31.00    0.00    178408.00  5755.10
644.40      2183.87 116.13  36.00

178408wsec/s = 178408*(512/1024) =89204kb.

89240kb / 31 = 2878 kb. (huh!)

4. sun solaris , ufs file system :

time dd if=/dev/zero of=/data/spss/test bs=4096k count=100

real    0m6.206s
user    0m0.000s
sys     0m2.830s

                  extended device statistics
device       r/s    w/s      kr/s   kw/s       wait  actv  svc_t  %w
%b
sd81         0.0  241.6    0.0   47195.2   29.7  11.9  172.2  24  74

47195,2 / 241.6 = 195 kb.

These results are also interesting .

Chao , i have tried the sql statements by stopping one of the nodes , the duration did not change. I think this is also clear from the statspack output which shows lots of global cr request events but its wait time is very low.

Kind Regards,
tolga Received on Wed May 25 2005 - 09:43:44 CDT