Discussion Forums > Technology
Moving large amounts of data between HDDs... CRC "fail"?
kitamesume:
i don't know much about network transfers since i've given up on it, using USB externals as a medium of transfer at the moment, it never seems to fail even once.
so if a USB external HDD transfer isn't failing but a LAN network is failing, would that mean the fault is within the network? like the NIC or the router, or maybe LAN is heavily susceptible to interference?
rkruger:
--- Quote from: kitamesume on July 02, 2012, 08:36:06 AM ---so if a USB external HDD transfer isn't failing but a LAN network is failing, would that mean the fault is within the network?
--- End quote ---
Yes, sounds like a logical conclusion to me.
It should be possible to view statistics for the NIC, like the amount of transmission errors. That will give you a clear indication that there is a problem with the network or not.
--- Quote from: kitamesume on July 02, 2012, 08:36:06 AM ---like the NIC or the router, or maybe LAN is heavily susceptible to interference?
--- End quote ---
The first thing to check is usually the cabling itself.
Make sure that the network cables are away from any power cables, as they may cause interference.
If are able, try to replace the network cables with some other ones.
lapa321:
--- Quote from: rkruger on July 03, 2012, 05:52:10 AM ---
--- Quote from: kitamesume on July 02, 2012, 08:36:06 AM ---so if a USB external HDD transfer isn't failing but a LAN network is failing, would that mean the fault is within the network?
--- End quote ---
Yes, sounds like a logical conclusion to me.
It should be possible to view statistics for the NIC, like the amount of transmission errors. That will give you a clear indication that there is a problem with the network or not.
--- End quote ---
If the cable was causing data errors. Shouldn't the NIC and the network protocols be able to catch them?
Freedom Kira:
Not all transmission errors are catchable. You can make a CRC that catches up to n bits of error at a time (requires a CRC checksum that is n bits long) but it may not catch n+1 or more bits of error at a time (i.e. if n+1 bits are flipped in transmission).
At least, this is how I remember it from my networks class...
lapa321:
--- Quote from: Freedom Kira on July 04, 2012, 02:29:17 AM ---Not all transmission errors are catchable. You can make a CRC that catches up to n bits of error at a time (requires a CRC checksum that is n bits long) but it may not catch n+1 or more bits of error at a time (i.e. if n+1 bits are flipped in transmission).
At least, this is how I remember it from my networks class...
--- End quote ---
Same here. Error detection is not perfect, and certain errors will still register as correct if the checksum of the error is identical to the correct one (CRC is not a byte comparison). The odds of that happening is incrediby small, but we deal with terabytes of data so it's unavoidable that an error will occasionally slip through.
BTW, i've only found some NAS utilities, but i can't use them for burn tests since they only seem to do thoroughput performance, not data integrity since they don't seem to do byte comparisons. Still need to search some more.
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