Facing high I/O wait in apache tomcat server when the load increases. Suspecting disk I/O is less when tomcat is running however. disk IO seems drops drastically when tomcat is running along with the load. Other resources(CPU,RAM) are under utilized. Unable to find the reason. Kindly suggest.
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iotop, inotifywatch are nice tools. Also to trace all file systemcalls of tomcat, you could use `strace -p tomcat-pid -f -e trace=file -o output-file`. Is there perhaps some database application running inside tomcat that wants to log transactions? sdc seems to have the highest wait times. Is there any lvm or raid across the disks? Is tomcat the primary load of the machine? – Gerrit Nov 30 '21 at 16:52
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No database appllication running inside the tomcat. Yes sdc is a lvm. and tomcat itself is the primary load of the machine. – Sandesh Bailur Dec 15 '21 at 05:00
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The write throughput on sdc is considerable (depending on the hardware of course). To get a feeling for what is writing use iotop and jcmd from Java JDK. With `sudo -u tomcatuser jcmd pidoftomcat Thread.print` you can get a good idea of what actions Java is taking at that moment. – Gerrit Dec 15 '21 at 15:44