n9hmg
ADSM.ORG Senior Member
- Joined
- Dec 18, 2006
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- 594
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- Location
- northern front-range Colorado, USA
I thought I'd found the solution to our backups failing on bad CRCs (due to WAN corruption), by accepting the waste of sending and storing every RMAN chunk twice by enabling the TDPO_MGMT_CLASS_[234] in tdpo.opt and running RMAN backups with duplex. I was down to trying to figure out how safely discard the unneeded redundant copies once made, when in further testing, a duplexed backup failed. One of the two channels failed, so the whole backup failed. So, rather providing redundancy, duplex provides additional points of failure.
So, does anyone else have a way to pre-protect TSM data transfers? Yeah, TCP uses a 16bit checksum, so the chance of an invalid packet not being discarded for bad checksum is only 1 in 65536. But that 65535 in 65536 per bad packet chance of catching the bad packet starts to look pretty bad after a few bad packets... at 45426 packets discarded for bad checksum, the probability of failure reaches 50%.
I'm about ready to do tunneling for the TDP backups (baclient fails one file and keeps going).
So, does anyone else have a way to pre-protect TSM data transfers? Yeah, TCP uses a 16bit checksum, so the chance of an invalid packet not being discarded for bad checksum is only 1 in 65536. But that 65535 in 65536 per bad packet chance of catching the bad packet starts to look pretty bad after a few bad packets... at 45426 packets discarded for bad checksum, the probability of failure reaches 50%.
I'm about ready to do tunneling for the TDP backups (baclient fails one file and keeps going).
