So Newegg’s been having networking gear on sale recently and I picked up:
D-Link DCM-202 Cable Modem
NETGEAR GS608 8-Port Gigabit Switch
There were a couple reasons why I decided to pick these up.
First of all, they were on sale. The NETGEAR Gigabit Switch featured jumbo frames and I wanted to see if I could get better speeds with my gigabit setup. Apparently not much. I was able to hit over 25% network utilization with the new switch, which leads me once again to believe it’s my RAID5 configuration causing the slowdown. I do however now have 7 gigabit ports instead of just 4 (1’s taken by the cross over connection to the router).
The reason I picked up a cable modem was I’ve been getting pretty crappy speeds with Comcast. I have a 8Mbps service which I pay $35/mo, but I usually get ~4Mbps. At first I thought it was my location, but after moving to my new house, it was still the same speed. I decided to get a new cable modem for 2 reasons: to see if it’s really the modem’s fault for the slow speed and to not pay the monthly modem lease fee of $3.95/month or something like that. Even if the speeds didn’t get any better, the modem would’ve paid for itself in 9 months.
Anyway, after calling customer support and switching my account over to the new modem’s MAC address, I did a speed test at Broadband Reports. Guess what! Instead of reporting 4xxx kbps down and 4xx kbps up, I’m got 7548 kbps down and 693 kbps up. So my modem was the culprit! I’m going to return this piece of crap RCA modem that Comcast gave me back to them later this week.
So Esca tried to help me with my Gigabit problem yesterday and made some suggestions. He first wanted to know if my switch supported jumbo frames, which is the reason I got the new Netgear switch. He had asked if I had enabled it on XP and if I recall correctly, Windows automatically detects what’s the best MTU (Maximum Transmission Unit) size to use. I’ve been blaming the slowness due to disk writes and RAID5 is notoriously slow for writing, but he suggested I try to grab some files over FTP and save into /dev/null. I went about this through cygwin as my Linux box doesn’t have a Gigabit adapter and was getting 26MB/s. I grabbed it several times hoping that the file would be cached.
Anyway, I ended up changing the MTU in the registry, rebooted my machines, and did a FTP transfer before starting any internet apps. I hit a sustained 33MB/s. Guess I’m happy now. Setting a MTU size was rather easy. Just open your registry and add a DWORD to HKLM\System\CurrentControlSet\Services\Tcpip\Parameters named MTU and set it to 9000 (decimal), 9000 being the packet size you want to use with Gigabit ethernet.