Re: analyzing, visualizing, understanding and rating I/O latency
Date: Thu, 2 Aug 2012 03:16:56 -0500
Hum. I have a customer now in which average write times are over .030 seconds and read times are over .015. Pretty slow when compared to other customers. But guess what? Nobody complains, ever. My thinking is IO is slow = "when customer is not happy with response time" and "response time > 25% of total transaction/batch job time" and "read times > .015 and write times > .030" and "weight more heavily if the job/transaction generates a lot of writes".
Avg latency if prob fine, assuming this is not a first person shooter in which a single long latency event could have catastrophic consequences for a single user. So depends.
If you are just dealing with a "normal" system then what you want to look at is events "way outside" the range of normal, so for example, a SQL which normally runs in .1 seconds which all of a sudden takes 20 seconds. Now that is an issue and you want to know why it went from .1 seconds to 20 seconds. If you are running a good SQL monitor you will get reports about events like this. Ideally you will even be able to confirm SQL X corresponds to business transaction Y and this is important/unimportance because...another thing to monitor for would be a SQL which normally runs in .1 seconds which all of a sudden runs in 2 seconds...(and a bunch of other SQL's do the same thing all at the same time)...now what caused that? That is something you should be monitoring for...especially if your host is "in the cloud" so to speak.
On Mon, Jul 30, 2012 at 1:47 PM, kyle Hailey <kylelf_at_gmail.com> wrote:
> Two questions I'm interested in answering or getting opinions on are: