ioping

If you've been to my blog before, you probably noticed that I spend a lot of time dinking around with hard drives and ssds, not to mention Cassandra performance tuning. I've done a fair bit of work with fio and it works OK, but it's not the kind of thing you want to run on production servers and even then, it takes a non-trivial of work to devise a config, run a test, then analyze the output. So, I've been looking for a simple tool to quickly assess a storage volume's latency. ioping(1) seems to fit the bill.

Like ICMP ping, it's useful for getting a rough idea of what the RTT to your storage. It's a single package manager command to install it and it provides that 'quick sniff' view of a system's storage that I've been searching for.

I grabbed a 7200RPM Seagate Constellation SATA drive off the shelf and plugged it into my SAS bay. This model of drive is commonly shipped in enterprise servers.

This experiment took all of 30 seconds to run. About 2/3 of the way down you may notice that latency went from ~8ms to 1.58 seconds. What happend is that I started ioping then flipped to another screen and ran one of my favorite read load tricks:

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