DreamHost PS Troubleshooting
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Contents |
Symptoms of an Overloaded DreamHost PS
If you experience any of the following symptoms, most likely you will need to increase the resource allocation (CPU & memory) to your Private Server:
- Out of memory
- Internal server errors ("500" errors)
- Killed scripts
- Inability to log in ("ssh_exchange_identification: Connection closed by remote host")
Checking your Daily & Monthly Resource Usage
Check the daily & monthly usage graph in the Control Panel under (PRIVATE SERVERS > CPU/MEMORY) to see if your usage is going beyond your currently guaranteed CPU and memory allocation.
Changing your CPU & Memory Allocation
You can increase or decrease your resource allocation by moving the green slider in the Control Panel under (PRIVATE SERVERS > CPU/MEMORY). As you move it the amount of CPU and memory will update automatically, along with the rate you'll be charged for that setting. Once you're happy with the setting click on the "Change {servername}'s CPU / Memory Now!" button to push the change into place. It will take a short period of time for the setting change to be reflected. Typically no reboot is necessary.
Rebooting your DreamHost PS
If you have a problem you can try rebooting your Private Server yourself in the Control Panel under (PRIVATE SERVERS > REBOOT SERVER). No need to contact support for that! Isn't that cool?! It may temporarily fix things, but if it doesn't provide a long-term solution, you will need to increase the resources allocated to your Private Server by using the green slider as mentioned in the previous paragraph.
Overloaded DreamHost PS
The image above is what your daily usage graph might look if you've got your settings too low. Notice that the actual usage routinely exceeds the guaranteed amount of 150MHz/MB. This is bound to cause problems for your sites. To rectify the situation it's recommended that you increase your resource allocation. Then keep an eye on the graph for several hours, and test our sites to see if you've allocated enough resources for things to run smoothly. It is recommended that you start out by doubling your current resource allocation to see if it's enough. Once you've verified that things are running properly you can reduce your resource allocation to the point where your peaks just barely exceed what you have allocated. Of course you'll want to routinely monitor your usage and increase the resource allocation as your needs increase. It's best to over allocate then under allocate! You don't want to find out that you've under allocated by your visitors/customers complaining about your sites not working properly.
Note that you're only charged for the period of time that you have the slider in a particular position. So it's safe to experiment. In fact, we recommend it. You can increase or decrease your resource allocation at any time.
You will typically see Apache processes running on your server and appearing to consume all of the memory. This is generally not the case because Apache processes share a significant amount of memory between one another. Additionally, we automatically configure Apache to work well within the memory allocation of your PS server. It is still possible for a busy website to overwhelm a DreamHost PS server, but it is not generally the fault of the apache webserver itself.
Of course you may also want to try to reduce your load on the server as well so you can reduce the resource allocation and save some money.
See this section in our Wiki for more information on reducing your CPU_Resources.
Idle DreamHost PS
The image above is what your daily usage graph might look if you've got nothing running under your DreamHost PS. This just shows the overhead resource usage. You could host a lightly loaded web page with this resource allocation (provided it uses static content), but probably not much more. If you've got your resource allocation set to 150MHz/MB it is recommendended that you monitor the usage very often.
Changing web server
Apache webserver on DH is configured in process-based mode. This means that each process serves one simultaneous connection and uses significant amount of memory for that, thus limiting concurrent user count. You can download and install some lightweight web-servers like (lighttpd) or (nginx). These servers use async i/o and can handle large count of concurrent connections without consuming much RAM, especially when serving static files. But default port 80 is already occupied by apache, and you cannot change that. So, you can use another port for new lightweight server, but visitors will see ugly port number in address and such solution will not work for some corporate firewalls.
(nginx) and (fnord) servers are proven to work on Dreamhost PS without any problems.
