FORMATING !!! For some reason, the TAB sign has been replaced with 09 (HEX) thus all my numbers were prefixed by 09 !!!! I knew i didn't post these numbers ... Here's the results with NO TABS Random read from my SAN Test type Responce time (ms) 512 read-1 0.874 512 read-2 0.173 512 read-4 0.130 8k read-1 0.457 8k read-2 0.149 8k read-4 0.228 32k read-1 0.422 32k read-2 0.388 32k read-4 0.762 256k read-1 2.165 256k read-2 2.672 256k read-4 5.185 I dont have the 512K reads saved. The number after the test is outstanding IOs. (read async or multiple sessions active). And the random values are: 512 read RAND-1 252.949 512 read RAND-2 79.780 512 read RAND-4 7.537 8k read RAND-1 6.376 8k read RAND-2 6.978 8k read RAND-4 8.375 32k read RAND-1 7.193 32k read RAND-2 8.399 32k read RAND-4 11.864 256k read RAND-1 1.331 256k read RAND-2 15.278 256k read RAND-4 27.275 On 5/18/05, Paul Drake <bdbafh@xxxxxxxxx> wrote: > On 5/18/05, Christo Kutrovsky <kutrovsky.oracle@xxxxxxxxx> wrote: > > Wolfgang, > > > > I will have to repeat this test on my system. What was your OS and > > file system ? linux and ext3 does not have directio support. It also > > has poor default read-ahead parameters. > > > > "...on average it should take the same amount of time to position ..." > > If you were to do 1 x dfmrc randomly, then yes mread would always be > > > sread. But you are doing this sequencially. Thus only the 1st read > > would involve positioning the heads, after that, every subsequent read > > would not include that time. Every so often, there would be some time > > to move the head to next track, but this time is far less then a full > > seek time. That is, of course, assuming no other disk activity. Or > > minor activity. > > > > Unfortunelly the test 10g system I have is not yet on the SAN i am test= ing. > > > > I am using RedHat linux and ASM (i.e. using directio) > > > > These results have been produced with Windows (for convenience) on > > unpartitioned drives with iometer (www.iometer.org). No caching on OS > > side. > > > > Random read from my SAN > > Test type Responce time (ms) > > 512 read-1=3D090.874 > > 512 read-2=3D090.173 > > 512 read-4=3D090.130 > > 8k read-1=3D090.457 > > 8k read-2=3D090.149 > > 8k read-4=3D090.228 > > 32k read-1=3D090.422 > > 32k read-2=3D090.388 > > 32k read-4=3D090.762 > > 256k read-1=3D092.165 > > 256k read-2=3D092.672 > > 256k read-4=3D095.185 > > >=20 > 90 milliseconds for a single IO? what are you using, a 5 year old laptop? > Can you run a sanity check against sys.V_$FILESTAT to make sure that > you're on the right order of magnitude? >=20 > This sounds like you need to watch the movie "Office Space" repeatedly. > Pay particular attention to the part where Micheal Bolton is chastised > for not keeping proper track of the decimal (US-centric) point. They > end up headed for trouble, but predictably so as the movie came out of > hollywood, they avoid _hard_ time in a federal (pound me ...) prison. >=20 > You cannot be averaging 90 milliseconds for an IO on a healthy system. > I don't think that I could get that if I set every parameter > backwards, disabled all of the indexes and set the > pga_aggregate_target to 4M. Guess it might be worth a try. > I guess that its possible if you are running RAID 5. baarf. >=20 > Paul >=20 > -- > #/etc/init.d/init.cssd stop > # f=3Dma, divide by 1, convert to moles. >=20 --=20 Christo Kutrovsky Database/System Administrator The Pythian Group -- //www.freelists.org/webpage/oracle-l