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Is there any effect on the performance of your servers if you exceed RAM?
consolepark
Member
Most of the companies in market provide extendable RAM feature to attract the customer, but is there is any effect in the performance if they exceed the RAM ?
Comments
@consolepark where are you from? Which country?
@ rds100 From Concord, California, USA
Do you mean dedicated / guaranteed ram vs burstable RAM?
If you're using burstable ram, there's no performance cost. It's just that burst ram is not guaranteed.
Good to know. I was trying to figure out whether your previous history on LET is due to language barrier, or there is something else.
Curiously he want to know more deep than VPS topic
To a certain extent more RAM does == good (laugh along with me) but there comes a point where adding more RAM will not affect the performance any more. RAM is just where things that the computer is currently using are stored, more RAM more space to store things, but if you have way more space then is needed that left over space is essentially wasted.
Unused space is used to cache files and such by the OS. The amount the OS uses it to cache varies depending on how much RAM there is and how much is free, but it does get used for caching.
When you use too much RAM, it will swap.
When you don't have (enough) swap it will start killing processes.
When you do have swap but use regular SATA drives, chances are your performance does actually get apeshit (granted that data will be accessed actively)
Thanks for the reply & great information that not only helps me in understanding, but also helps other when the choose their VPS service.
Sometimes, I feel that the best way to know would be to experience it yourself.
If you would like to experience it yourself, install any linux distribution of your choice, make sure that swap is enabled(free -m and you should see swap with its amount of "memory"), and try to load your computer with heavy RAM applications(firefox, chrome, etc) until it is ~80% loaded and you'll notice your computer will start to slow down as swap is being used(ensure that your vm.swappiness is 60 or higher via sysctl vm.swappiness).
To temporarily recover your system:
sudo swapoff -a (and enter your account password)
sudo swapon -a
and feel the speed again
NOTE: you may notice the slowdown even before you reach 80% of your RAM usage, your usage will vary depending on your hardware spec.
NOTE #2: It would be better if you've tried this on a graphical user interface mode instead of console based so you'll feel the slowness yourself