OS is Debian Squeeze, Dell 2950 2 x 4 cores (8 cpus), 16GB RAM. 2 x Broadcom and 2 x Intel Gigabit cards. Dedicated environment. No virtualization.
My bandwidth with the ISP is about 10MB/s (10000 Kb/s). I use a iftop as the util to monitor the bandwidth coming in and out of the server
OS is Debian Squeeze. I did load impact test and found the virtual servers on Virtualmin could not surpass 3MB/s.
I have another web server running under Hyper-V in windows, load impact test on that server hover around 3-4MB/s, and often go to 7MB/s or 10MB/s.
I disabled iptables just to rule out any possibility. It made no difference. The websites under the virtualmin server cannot surpass 3MB/s majority of the time. Sometimes, it could go to 3.4-3.8MB/s, but only for a second, then it drop back down to 2.5 MB/s.
Using another server on a local network, I test upload a file via the Webmin file manager, upload is fast 24MB/s. Then I try downloading the same file, the speed simply could not exceed 4MB/s.
I switched to using Bitvise Tunneling software to do a straight SFTP transfer via SSH. The speed in and out of the server is 175MB/s to 185MB/s. This is straight copying between the two servers on the same local area network.
This rule out one thing. It's not a network driver issue with Debian as it proved to transfer upward of 175-185 MB/s.
I am using Webmin file manage to download the file from the server. Browser is firefox 4.
My question. Why is it so slow to download? Even upload, it supposed to be way up there at 175-185 MB/s. Instead, it hover only at around 24 MB/s? For download, it crawled to no more than 4MB/s.
Downloading is traffic going out of the server. Uploading is traffic coming into the server.
I don't have enought time. But plan to test with cPanel and others to see if I run into the same issue. I also plan to test on a server without virtualmin or webmin installed. But configuring everything manually may prove to be a real pain.
I would love to hear from someone about this issue. Thank you in advance for your help.