Questions USB

[Charles]

Good morning

I have two candid questions on USB connections.

First, if I add a USB1 device on a USB2 hub on which other USB2 devices
are plugged, will the whole system work in USB1 or will it keep working
on USB2? Same question on the motherboard: there are several
connectors, are they really independent, or if I plug a USB1 device on
one of the connector, will I force the whole card to work on USB1?

My second question is about the stability of the hard drives connected
in USB. For some reasons I often get some error messages like "delayed
write failed". It's a new PC, but the hard drives were working just
fine on the old one. In which direction should I investigate? A faulty
motherboard? Bad drivers?

I thank you in advance if anyone can help
Charles

 

[Mike Williams]

My second question is about the stability of the hard drives connected
in USB. For some reasons I often get some error messages like "delayed
write failed". It's a new PC, but the hard drives were working just
fine on the old one. In which direction should I investigate? A faulty
motherboard? Bad drivers?

It's hard to know where to begin with those delayed write messages: they
show up on USB1, USB2 and Firewire. Are you using a Maxtor drive?: they
have been the main culprit in my experience. I've never had the message
with other drives.

 

[R. McCarty]

USB1(.1) and USB2 work independently. Internally on the MB, the
USB is routed. On most implementations, there is a single enhanced
controller and several Standard or Universal controllers. All USB 2
devices connect and run from the single enhanced controller. All of
your USB1(.1) devices will route to a dedicated controller based on
which socket you plug your device into.

Contrary to popular belief, a USB drive (Rated at UP TO 480 Meg)
really only transfers data at or below ~25 Megabytes. USB Drives
are all designated "Removable" by XP and can operate in one of two
modes or Policies. Likely the device has it's Write Behind cache turned
on. In many cases using a USB drive in "Optimize for Performance"
will cause those delayed write failures. Best to toggle it's policy over
to "Optimize for Quick Removal" which turns off the write caching.
Use Device Manager, Disk Drives to locate your unit and you'll find
a Policies (TAB) where you can make adjustments.

 

[Charles]

Actually the faulty drive is a Lacie big disk drive. It's an external
drive that includes actually two disks. And it seems the error occurs
regardless of the source of the files.

It's running on windows xp.

 

[Mike Williams]

In many cases using a USB drive in "Optimize for Performance"
will cause those delayed write failures. Best to toggle it's policy over
to "Optimize for Quick Removal" which turns off the write caching.
Use Device Manager, Disk Drives to locate your unit and you'll find
a Policies (TAB) where you can make adjustments.

I never found that this made a difference with large external HDDs (and
which usually have write caching turned off already). Thankfully my
current external drive (a Seagate) has never had the problem which each
of my Maxtor drives had in spades.

 

[Charles]

Thanks for the answer. So if I understood, you can connect on a MB a
USB1.1 device on one port and a USB2 on another port, and both will
work at their maximum speed.

On the other side if I connect a USB1.1 device on an external USB2 hub
with other USB2 devices, the whole will work in USB1.1?

Charles

 

[R. McCarty]

No, If a Expansion Hub is USB2 then it can serve both High Speed &
Full Speed devices simultaneously. However, if the Expansion Hub is
a USB1(.1) then all devices used with it can only operate at the slower
mode. Bandwidth is perhaps a more limiting factor. Unfortunately, there
isn't a mapping/monitoring tool for USB other than one from Adaptec
that only works with their branded USB products. It graphically draws
the USB chains and shows speed of connected devices.