Hi All,

According to the graphs, I seem to be having quite high spikes in cpu usage. The site is having around 6,000 visitors per day and 5 mins browsing time and browsing 10 pages on average.
Linode 3072 (current plan) but I can't find where it shows how many CPU of this plan and RAM etc.
Shall I upgrade to the Linode plan with 8 CPU (8x priority) or 8 CPU (16x priority), does it help???

Here is the graphs

CPU


Traffic


IO

You can go up to 800% cpu, your disk io is nice and low. I don't see a need for you to upgrade. FYI all Linodes have 8 cpus. The larger plans have less guests per host so you have a lower contention ratio.

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I concur: it doesn't look like there's a problem with resource shortage. It also looks like CPU usage and network traffic are strongly related, so the spikes are probably just normal traffic patterns for your web site. You're also using a lot more than 100% when needed, which tells me that your application is actually able to take advantage of multiple processors -- this is a good thing(*).

For growth planning, I would start thinking about architectural changes so that you can scale horizontally (i.e. across multiple Linodes). You will not be able to exceed 800% CPU on a single Linode(**), and if you were to double your traffic, you're bound to start hitting that occasionally. This is not a problem that can be fixed by moving to a larger instance, another VPS provider, or even a dedicated server: there are physical (and practical) limits to how many cores you can put into a single server.

(*) My "real job" involves embedded systems, such as FPGAs. Simulating FPGAs is very much not something that can take advantage of multiple processors, so if I sound jealous, that's why.
(**) That's 8 CPU cores, each at 100%. Note that Linode NextGen hosts have two 8-core processors in them, for a total of 16 cores. Consider 800% a limit like the speed of light: the more you pay, the closer you can get to 800%, but you can not exceed it.

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Hi thanks for your reply, please see this error report in our google webmaster tool, we thought the vps has connection problem and cause google bot can't access our website, any idea?

And you said 800% cpu, so 300% mean our website only use 3 cpus? I thought for example we have 3x priority then we are using 3x*300%=9 cpus.

Your site is essentially using 300% of the potential 800% available to it. That is when the other nodes on your host aren't using their share of course.

What do your error logs say when you have errors?

Charts are somewhat useless for determining what the actual problem is.

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Your CPU usage is fine. All plans currently have at least 8 cores. When it starts to reach 700% constantly is when you may want to look at splitting the node into two linodes. If you have not rebooted since the CPU core increase, you may still have 4 cores visible to the linode (stong reason since your charts only seem to show 400% as max available).

Unless you are in Fremont, you may be eligible for a free ram upgrade (double your current plan if plan activated before April 9 2013). Fremont should get it sometime soonish...

If you are in Fremont and the errors were on Fri April 26 from ~ 14:20 EDT to ~15:45 EDT then the issue was a network connectivity issue with fremont: http://status.linode.com/2013/04/fremon ... ssues.html

If it has been a while since you restarted the machine you may have some unused upgrades.

as of Dec 14 2012: All plans got 20% additional disk space. (Disk resize required to use on current disks, or just create a new blank disk and add it to your linode. Reboot required to "attach" disk to linode.

as of March 7 2013: All plans got 10x bandwidth limits (automatic)

as of March 18 2013: All plans went to at least 8 cores (reboot linode required to activate/detect)

as of April 9 2013: All plans doubled RAM; moved to better CPUs/architecture [except for Fremont]. Special Upgrade button in manager will appear when it is available to your linode.

This is all true (about having up to 800% CPU usage available) except if other people on the host are doing the same thing, you'll never get to use all that CPU time and your performance will be terrible (high steal CPU %). If you are on a lightly loaded host, you will be fine. If you are not, then all bets are off.