Hi everybody,
I am a french Web developper. My application is mozilla-based and running
under :
-Fedora Core 3 - kernel 2.6.10-1.741_FC3smp
-Apache Web server 2.0
-CPU Intel Pentium 4 HT 2.8GHz
-Dell Server PowerEdge SC420
-Usb controller = Intel ICH6 82801 Series Rev 3
For one of my company's customer, I have to build an application which is
able to create dedicated USB disks. Inn fact, the customer use the Dell
Server as a usb disk generator. These disks (all Plextor PX-PH 40 or 80Go),
must be formated to EXT2 and then a daily generated TAR file, which may vary
between 1 and 20 Go, must copied on each disk.
For instance, the process is sequential : each disk is made one-by-one which
was working very good because no conflicts but, as you will have understood,
too slow. With file of 17Go and 16 disks connected on the server, it may
take up to 5Hours to complete all disks.
My application managed to launch multiple jobs on USB disks (thanks to
XMLHttpRequest objects). Everything work well if there are not any hardware
failure (USB disk full or other...). But it's getting harder when handling
errors.
One can plug up to 16 usb disks at once. these disks are dispatched on 4
4-ports USB HUBs (brands are not relevant, they work very well).
My problem is :
When doing multiple simultaneous jobs on disks (formating,
copying...)and
unplugging one disk while doing these jobs : my server is completly unable
to handle I/O errors. Some disks continues their jobs as if it was no error,
but most of them are blocked. In fact, format or copy processes are Dead,
they run in loop and do not respond to a kill command. The server goes in a
dead-lock and even all reboot/shutdown commands do not complete because
filesystem is busy. Need to shutdown the server by the button.
Steps are :
1. plug several USB mass storage : at least 6/8
2. launch simultaneous commands "mkfs.ext2 /dev/..." on each one i.e:
with
terminal tabs
3. To simulate a manipulating error, unplug (while formating) one or
more
usb disks.
4. Type "ps auxfww" command to list cp or mkfs processes
5.
Does anyone have an idea of that behaviour?
May it come from kernel version, smp or USB module ?
I know that USB is a sensitive part of hardware to handle.
Nicolas Macquet
Développeur R&D
email : [EMAIL PROTECTED]
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