I have centOS box with 1 x dual core CPU in it. The load average is between 1.5 and 3. When the traffic is on top the load average is between 2.5 - 3.5. Is it necessary to upgrade ? Server seems to be respond fast. Also I heard that Top command on centOS with dual core CPU doesn't show exact values. Anybody know something about that ? Thank you.
There is no simple answer to your question. What we generally advise is that people look at their traffic patterns for the last 6-12 months, and do a best guess on their projected growth, factoring in historical growth, and any differences in their promotional plans for the site.
If there is a valid reason to anticipate meaningful continued increase in load, our recomendation is to move now, when you are affecting less users. To wait until you have to move only puts you in a position of negatively affecting many more users. We would rather see you plan for a quick cutover from good performance to better performance with very little impact, rather than wait until service degrades for more users, and then scramble to get something done.
If your pattern has been steady for a long time, and you are happy with performance, stay where you are.
Thanx for answer. We use 1 x Xeon 5130 (dual core). But the mainboard can hold 2 x 4core CPUs . So when we bought machine we wanted to have some upgrade availability. Also we use RAID10 with 4 x 15K SAS drives in it so it seems to be fast. RAM = 2GB. Machine currently serves about 160.000 visitors/day. We did some marketing last month... It was only about 100.000 uniques/day in December.
You have lots of headroom there then, and you have done a good job planning for the future. Based on those specs I would look at bumping up your RAM before CPU's, although you may want to drop another CPU in while you are plugging in the RAM.
That is a nice response on your marketing. If it is profitable and you intend to keep the marketing up, it might be worth making the changes before the next major marketing push. Just a thought...