When I use sysbench to test mysql, I use iotop to monitor io and I find only have DiSH WRITE speed, the DISK READ speed is always 0. Then I use free -h and I find that buffer/cache increase, does it mean that sysbench's test data is not write in disk but in buffer and no auto update into disk?
Thank you so much!
where is the mysql running ?? I dont know about iotop and what its measuring but even tiny sysbench runs generate enormous IO. it could be a user issue maybe, perhaps mysql is generating io under a different user and not getting picked up.
# you can isolate the db into a container and run sysbench against this to see
# if/when/how much IO there is.
docker run --rm -it --name mdb105 --network host -e MYSQL_ALLOW_EMPTY_PASSWORD=on mariadb:10.5 --port=10306
# in another terminal run
docker stats
# now run sysbench, and you will see enormous IO
# you can get another shell in container named mdb105 by:
docker exec -it --user root mdb105 bash
# mariadb:10.5 is based on ubuntu:20.04
# you could maybe run iotop inside the container
Update: I was able to replicate something like your zero IO situation using a raspberry pi. indeed docker stats shows no IO while clearly data is being saved to disk. my initial reaction was that maybe some kernels/distro are missing certain facilities, but it looks like its not kernel/distro because i saw IO when playing around with disk/fs ie extenal USB disk ... i think it was more to do with the micro sd card and its controller/drivers that dont support this kind of stats. and since your tps is very low i suspect you are on something similar to micro sd as well.
this likely wont happen in a ec2 instance.