Hi,we have a few LHS storage nodes in our environment. i ma not having any performace issues at the moment but i am looking at the performance counters on the SAN.
i understand that every environment is differenent and workloads differ from company to company. does any documentation exist that defines what is good and what is poor performance. For example if we have IOPS of 6000 on the SAN. would this be bad. If latencey was higher than 20ms would this be classed as slow. again some companis might have an IOPS sla of 15ms making 20 slow. suppse i am looking for some technical documentation on whats good and whats bad.
it all depends on your setup. I wouldn't use IOPS as that is dependent on your load profile. There are some general IO numbers for physical drives so that should give you an idea of the max theoretical IO of your system assuming 100% random IO,
IO latency during periods of normal load is probably a better indicator. 20ms is probably ok for 7200RPM drives so if that is your setup that is probably fine. I would also watch que length to make sure it doesn't run too high out of control. both IO and que depend on the number of drives and speed in your setup so I can't give exact numbers here, but I"m sure you can find the formulas with a little google query.
The figures don't mean much without knowing your exact setup (number of nodes, type of nodes, type of drives, number of network connections, 1Gb or 10Gb, etc) but here's some conventional advice... if it isn't broke, why look for a problem?
You said you're not experiencing any performance problems, so why go looking for them? Typically, I like to think performance indicators only really matter if there are complaints about performance. It'd be like me complaining about my Nissan Altima not having 400hp and being unable to race a Mustang - at the end of the day, I didn't buy it to beat the Mustang, I bought it to get me from point A to B, which it does and does very efficiently.
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