XServe is slow over 100MB/s switch

Question

I have a big problem that's getting bigger by the month. My LAN is sloooowww! I am the assistant (i.e. volunteer technology coordinator at a small private elementary school and we are using a Dual G5 XServe (all the latest patches) for our main server. We mainly use it for authentication (OpenDirectory) and file sharing (SMB). We have 200 WindowsXP machines shared amongst 500 students using roaming profiles.
Our problem is that logging in/out of the LAN is taking 4-6 minutes and that's way too much time to sit there with Kindergarten grade students! We've limited profiles (although we are still trying to reduce them further) and tried several other things on the Windows side but nothing seems to help. I've monitored the XServe's resources during the day and it never seems to break a sweat in either CPU, Disk I/O, or network activity. The only thing I can think of right now is that our backbone switch is an old Xylan 100MB beast with not Gig interfaces. This means that both Ethernet ports coming off the XServe are only running at 100MB each.
I think our problem is that we are pushing waaay too much data through a 200MB pipe. Does that seem correct? My first thought was to upgrade the switch to a Gig model, but the expense (even @ eBay prices) of getting enough 1000MB ports to cover the school buried that idea real quick. And I can't seem to find a Gig interface for the Xylan anywhere!?!? What other options do I have? Break down and get a second XServe (but what would we use it for)? Segment the LAN and try to find a way to make the majority of the systems hit the server at Gig speeds?
I know this is a long message but I am really out on a limb here. Anybody with some networking mojo wanna spread some around?
Thanx!
Richard

Answer 1

Hi Corrado-
That is quite a few machines to manage and should be commended for undertaking this project as a volunteer (:>)
You may indeed need a new server, but I think you should take a close look at your network issue first. That switch is getting a little long in the tooth. Even one bad port can slow things down. If you can budget a new server then me thinks a new switch would be a bunch cheaper.
Is this a new issue or the way it has been for a while? Does powering down the switch and bringing it back online speed things up? The answer to those questions can steer you in a couple of different troubleshooting directions.
Do you allow connection to the internet through your setup? I am presuming that you do but I don't want to overlook anything. I do know that PC's running bit torrent software can hog a huge amount of bandwidth. Now I know that this is an elementary school but kids are smart and figure stuff out, especially the sneaky stuff, pretty quickly. You may want to shore up your filtering and or firewall defenses.
I would suggest powering down the entire network, server, and client machines. Bring the switch and server back up first. Go to a classroom or media center and power up 2 Macs and go through the log in and see what happens. If this is speedy this will be a hint.
That's all the mojo I have for now. Post back with your results if you need further assistance.
Luck-
-DaddyPaycheck