Take the 2-minute tour ×
Server Fault is a question and answer site for professional system and network administrators. It's 100% free, no registration required.

i have a server with 512MB RAM running mysql and apache service. I have joomla site inside my server. I want to ask,

  • is there a brief threshold limit of RAM when the server will be stated as busy? like if my server used RAM is 90% can i say that my server is busy? or other percentage threshold?
  • how much load can server with 512MB RAM handle?

i need consideration for server upgrade. thank you.

share|improve this question

closed as not constructive by mdpc, Michael Hampton, David Schwartz, Khaled, dunxd Feb 21 '13 at 11:33

As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance.If this question can be reworded to fit the rules in the help center, please edit the question.

    
add comment

2 Answers

up vote 0 down vote accepted

Technically speaking, RAM usage going above 90% is not much of a problem. The problem is when you see some real measurable performance problems because of it.

Keep an eye on the swapping stats, if you see too much si and so value in vmstat output combined with a high %sys value in top output, the CPU is spending most of it's time in bringing stuff in and out of disk and memory and that is a thrashing situation. That should be avoided at any cost.

Other than that, if you see most of the RAM is simply in cached state, then ignore it, it is the de facto behavior of linux.

share|improve this answer
    
thanks, it's not all about RAM, i've read that linux tend to use much ram for pagecache. but, what's possibly the cause when i have OOM message that turn off mySQL? do you have idea how much ram allocation mySQL need to handle request normally? –  initial05 Feb 21 '13 at 7:27
    
Show me the OOM messages and I can tell ;) –  Soham Chakraborty Feb 21 '13 at 7:38
add comment

No, just because memory is used doesn't mean your server is busy. Database servers load the databases into memory to make queries run faster than pulling the data from disk each time.

You can run commands like SHOW STATUS in the database engine to get a better idea of what kind of load is on that moment.

share|improve this answer
    
i have situation where mySQL service on my server is killed when handling requests. it said OOM error. what's possibly the cause? how much ram mySQL normally need? –  initial05 Feb 21 '13 at 7:30
add comment

Not the answer you're looking for? Browse other questions tagged or ask your own question.