RHEL 7.4 ext4 I/O permance issue compared to RHEL 5.11 ext3
What problem/issue/behavior are you having trouble with?
Below script is being used to do a disk performance test:
for i in {1..50}
do
sleep 2
sync
echo -e $i" \c"
dd if=/dev/zero of=$PWD/testfile oflag=direct bs=1G count=1 2>\&1 |\
awk -F, '{print $3}'|grep -v "^$"
rm -f testfile
done
This scripts shows a throughput of 1.4GB/s on ext3 filesystem at RHEL 5.11.
Running the same scripts on RHEL7.4 can reach on ext4 700MB/s and on ext3 550MB/s.
At first on xfs speeds of 1.2GB/s could be reached, but since a few days the speed drops to 880 MB/s and we have not found a way to get it fixed.
A Red Hat case has all ready been created, but I hope one of the Forum Members might know a solution.
Both VM's ran at the same VMware Datacenter during testing.
Responses
Guru
10133 points
Jan, have you tried interrogating the drives in question with lsof to see if there's something distracting the drive(s) in question? Just curious. I used to have an admin who for years ran persistent finds and we discovered it as one of the issues we were having. However, is there any chance some other thing like indexing (probably not persistent) or something else is nagging the drive that's losing performance?
Guru
6222 points
Hi R Hinton,
Thanks for the hint I see a load of messages stating no pwd for UID. https://access.redhat.com/solutions/483123 states these can be ignored.
hmmm shocking result: 2470 references to non existing linkable libraries. So I will check with the ISV if they are lifting a RHEL 5 based application and shifting it to RHEL 7 without updating the versions of Apache and Nagios, and other components.
Thanks for the hint.
Regards,
Jan Gerrit Kootstra
Guru
10133 points
Sometimes I'm the bug, sometimes I'm the windshield, glad I could help, you've helped me out of some jams Jan
-RJ
Guru
6222 points
RJ,
:) That is why the forum is called Community :)
I updated the RH Case and also sent the lsof output to the ISV to analyse.
Have a nice day (where are you situated?) I am in the Netherlands, so I will go to bed soon.
:)
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At 10 years you think I learned a lot, so I may know it all.
At 15 years you learn I can teach some of this stuff to colleagues
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:) So this 50 years old man can still learn even from the newbies. There is too much knowledge that you cannot gain from doing all the trainings.
Thanks,
Jan Gerrit
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