You're definitely pushing the limits of what you should be trying to do on a Linode 360, but you're not necessarily going too far yet. The actual amount of swap space you're using isn't what's important--it's how much data you're actually swapping in and out over a given period of time. You can use the vmstat utility to watch swap usage over time to get a better idea of what's going on. Below is the output of vmstat on my Linode 360 for six samples over a one minute period:
Code:
mt-elbert ~ $ vmstat 10
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
0 0 84 42764 45300 87132 0 0 0 1 1 0 0 0 100 0
0 0 84 42764 45300 87132 0 0 0 0 110 211 0 0 100 0
0 0 84 42764 45300 87132 0 0 0 0 108 211 0 0 100 0
0 0 84 42764 45300 87132 0 0 0 1 110 214 0 0 100 0
0 0 84 42764 45300 87132 0 0 0 0 108 211 0 0 100 0
0 0 84 42764 45300 87132 0 0 0 0 107 211 0 0 100 0
0 0 84 42764 45300 87132 0 0 0 0 110 212 0 0 100 0
The first line when you run vmstat is an average since boot, and the following lines are the number of operations occurring since the last sample. As you can see, my average swap i/o since boot is zero. This is good. If, however, you're seeing a high average, or if the swap operations spike significantly during periods of high load, you probably need to free up memory by running less processes or upgrading your Linode.
There are several tools available to monitor and graph your swap i/o over time that will help you determine if there is a problem that needs to be addressed. From what I've seen, Munin is pretty good for getting detailed data without too much setup hassle, but I haven't used it in a while. YMMV.
So, having said all of that, what really matters is monitoring your system over time to look for trends. Things like Munin are awesome for that as they allow you to see trends very easily. The trends you want to look for on a Linode, obviously, are things that cause disk i/o to spike since that is your most expensive resource from a performance perspective.
--James
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