USB problems?

I have an old computer with Win 2003 Server. It got 6 USB connectors. At four of them the Drobo connects (a drive letter is assigned and it is visible in an explorer) and gets disconnected after a few seconds. Half a minute later it connects again and then disconnects. This repeats forever.
The connection seems to be more stable at the other two USB ports. The problem is that writing seems to be in bursts. When I copy a large file (2GB) the progress indicator freezes about 4 times for a couple of seconds. Total time to copy is slightly more then 2 minutes. (Average speed about 15MB/s)

I would guess that the problem is in my computer, not the Drobo, but it is still a mystery to me. The USB drivers are standard Microsoft ones and they are not reporting any problem. Other equipment work fine at all 6 USB ports.

I have formated it to 16TB so I can’t test it at my Win XP workstation. I will try to borrow a Vista laptop and see if it makes any difference.

Are they front or back ports?

The drobo needs to be connected to back ports on a computer.

The drobo prefers it from behind it would appear.

Front ports sometimes don’t have enough power (for bus-powered devices, which the Drobo is not) and aren’t on the USB root hub. Sometimes they’re even completely separate add-on controllers just built onto the motherboard, but not part of the chipset!

Best to use the motherboard’s native controller (the ports soldered onto the motherboard).

It was the two in the back that worked best.

Now I suddenly get the same symptoms at all ports. Just connecting and disconnecting by itself.

Edit: The Drobo seems to be working with a Vista laptop. Could it be that the old motherboard got poor USB ports? Could it help if I used a shorter/higher quality USB cable? I am using the original cable now and I don’t even need half that length.

I’ve had motherboard USB controllers go bad on me before. What you’re describing sounds like what I experienced.

Open you system and check for leaking/bulging capacitors. If you see any, you should back up and look to getting a new system (unless you’re handy with a soldering iron). I had numerous systems with bad capacitors and it started with symptoms like you describe - flakey USB ports, then eventually the system got generally unstable.

badcaps.net has good pictures and info. They also provide repair services if it’s a special system/device that you can’t replace.

I changed most capacitors last year. Now it is steady as a rock. Maybe I forgot one or two of the small ones. I will take another look at it.

An alternative to spend $10 at a PCI board with USB ports. It is definitely less work.

The motherboard also have 3 Firewire 400 ports. Will it give a large impact on performance if I use one of those instead of USB ports?

You may see better performance using Firewire, especially if it’s the only device on the Firewire bus as it doesn’t have to share bandwidth with the other USB peripherals.

I know that Firewire 800 give she same or better performance compared to USB, but I only got Firewire 400. I believed it was slower then USB.

I will buy a 6/9 Firewire cable today and give it a try.

Firewire 400 is marginally slower than USB2.
Since USB relies on your computers CPU for its processing people often recommend that USB will give you slightly higher peak speeds while Firewire 400 will give consistent speeds.

If you have multiple USB devices or if you do a lot of CPU intensive work then Firewire 400 may give you consistently better speeds than USB2.
In real-work performance USB2 will top-out at around 35MB/second and Firewire 400 around 30MB/second.

Firewire 800 is much faster than USB2 or Firewire 400. It gives up to 60MB/second read and 35MB/second write. It is also Full Duplex which is better for reading and writing at the same time.
With a Drobo version 2 you won’t see much over 35MB/second anyway as it is limited by the power of its internal CPU.

ajspencer is correct.

While USB 2.0’s maximum bandwidth of 480 Mbps is faster than Firewire 400’s maximum bandwidth of 400 Mbps, in practice, Firewire tends to be more consistent in speed and less CPU-intensive compared to USB.

Of course, some of this is controller-specific, as there are different Firewire bridge vendors with chips of varying performance. Oxford tends to be the best in that class.

I bought a 6/9 Firewire cable. The communication is obviously not healthy because it works intermittently and becomes unresponsive at random. Two times the computer rebooted itself. The Drobo is still fine from the Vista laptop.

The mobo of the server is obviously toast. I changed all large electrolytic capacitors last year but I should have changed the small too. As it is now, I will probably just replace the mobo. Maybe I will buy a nice Firewire 800 board too.