Wednesday, September 9, 2009
performancewiki.com - monitoring disk io on aix, linux, windows, solaris
performancewiki.com - monitoring disk io on aix, linux, windows, solaris: "A couple of indicators must be monitored for hard disks in your system. Watch the Physical Disk (instance)\Disk Transfers/sec counter for each physical disk and if it goes above 25 disk I/Os per second then you've got poor response time for your disk. A bottleneck from a disk can significantly impact response time for applications running on your system, so you should investigate this further by tracking Physical Disk(instance)\% Idle Time, which measures the percent time that your hard disk is idle during the measurement interval, and if you see this counter fall below 20% then you've likely got read/write requests queuing up for your disk which is unable to service these requests in a timely fashion. In this case it's time to upgrade your hardware to use faster disks or scale out your application to better handle the load."
Tuesday, September 8, 2009
Technology Review: Faster File Flow
"In order to be smooth, which is what FastTCP does, you have to be more gentle and assess queuing delay," says Aleksandar Kuzmanovic, an associate professor in the department of electrical engineering and computer science at Northwestern University who researches TCP. By keeping the transfer from reaching the point of packet loss, he says, it's possible to avoid sending bursts of data, which can create a jittery effect for the recipient.
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