We're thinking about moving a series of high-volume mission-critical medical RDBMS from HP-UX to RHEL for cost savings and OS performance improvements, and have some RHEL/Linux questions...
Our beefy RDBMS servers are attached to a SAN and typically might have as many as 500+ long-lived server processes running concurrently, collectively processing 100 million+ queries/day. When we have an I/O bottleneck, it is very important that we are able to quickly identify which process(es) among many hundreds are most responsible and to what extent. It is *not* enough to simply identify the disk subsystem getting the I/O or guess by who's using CPU, interrupts, or by looking at process states, nor is it enough to look at per-process IO stats after the process has completed. We need to know the current quantitative I/O rates for each process while these processes are still running. On HP-UX, HP's Glance application provides that per-process I/O accounting (giving us I/Os per second). The relatively recently added CONFIG_TASK_IO_ACCOUNTING and CONFIG_TASKSTATS Linux kernel parameters provide what we need in Linux, but these do not appear to be enabled in RHEL 5. I see per-process IO accounting appears to have been enabled by default now in Debian, Ubuntu, Suse, and others. It's simple enough to rebuild the kernel. But I understand that rebuilding our RHEL kernels voids our RHEL support. There is considerable resistance to that in our organization. I find it hard to believe it is 2008 and this issue was not solved long ago in Linux given how critical this function is to performance analysis and troubleshooting. So what's the shortest/best path to getting live per-process IO accounting in RHEL? Can we pay Redhat to turn this on in a supported kernel for us? Other thoughts/suggestions? I'm aware of iotop, atop, and others, all dependent on these kernel parameters. Are their other Linux tools that do this job without the kernel reconfig? Thanks in advance. Ed _______________________________________________ rhelv5-list mailing list [email protected] https://www.redhat.com/mailman/listinfo/rhelv5-list
