[SLL] How to troubleshoot corrupted wget/apt-get/bittorrent file transfers?

[Derek Simkowiak]

    First, look for errors from the kernel in your system log files 
(kern.log, syslog, dmesg, etc.).  If there is a hardware problem with 
the NIC, the driver may have reported problems talking to the card.

    Then sniff the network and look for oddities.  Look for errors from 
upstream.  It might be a bad cable, bad switch, bad router... or an 
accidental induction coil formed by loops of power cables nested in a 
big pile on a desk :)

    If the network looks clean (no retransmits, dupes, broken packets, 
etc.), start running disk tests.  ...Especially the RAID stuff.

    If the disk tests are clean, check your RAM.  Write some big files 
to /dev/shm/, copy them, and compare MD5s, or boot off a rescue disk and 
run the memory check utility for a while.

    I'm guessing it's either the rat's nest, or the long CAT5 cable 
running from server to Timbuktu. 

--Derek


On 03/09/2009 06:26 PM, Kurt Buff wrote:
> On Mon, Mar 9, 2009 at 18:20, Phil Mocek <pmocek-sll at mocek.org> wrote:
>   
>> On Mon, Mar 09, 2009 at 05:03:14PM -0800, Kurt Buff wrote:
>>     
> <snip>
>   
>> It looks roughly like this: Cisco 678, with an old Webramp
>> something running Sonicwall SOHO firmware, both in a nest of power
>> cables, then CAT5 cable from there running over doors, across
>> floors, and down a handrail, around the corner, over some doors
>> and through a couple closets to a desk where there's some no-name
>> switch buried in a pile of network cables, power cables, and
>> various other gear.  Not pretty.
>>
>> But these are TCP connections.  Isn't any junk on the wire
>> supposed to be cleaned up at the transport layer?
>>     
>
> Heh. Not necessarily, though in theory yes. If there's an issue in the
> network, though, you'll likely see lots of retransmits and other
> errors. If that looks nice and clean, then it's somewhere in the
> hardware on the affected box.
>
>   
>>> But, one of the easiest things to try is a new NIC.
>>>       
>> Not if it involves a trip to the storage room to dig through "the
>> archives" to find a NIC, it isn't.  I haven't used a standalone
>> one since motherboards started coming with inbuilt NICs.
>>     
>
> Bummer. Well, if all else fails, a trip to the mathom room might be in
> your future.
>
> Kurt
>