From: Adam G. <mai...@we...> - 2008-07-15 03:17:10
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Holger Parplies wrote: > Hi, > > Peter Nankivell wrote on 2008-07-15 09:17:48 +1000 [Re: [BackupPC-users] aborted by signal=PIPE errors.]: >> [...] >> If it is all due to ssh and hardware it makes me worry about >> the resilience of ssh. Surely its protocol should be able to >> retry on corrupted data? I don't know... > > actually, TCP should provide ssh with a reliable data stream. If ssh *sees* > corrupted data, then either > > 1) the data has been tampered with or > 2) TCPs CRC failed to identify network data corruption. > > While (2) is conceivable, it should *not* be happening on a regular basis (if > it is, something else is wrong). I would guess it to be so rare that ssh > ignores the possibility, since there is no way to distinguish between both > cases. In the case of tampering, retransmissions would not make much sense > ("Hey, I noticed that! Be more subtle next time." :-). > >> Another solution maybe to use "rsyncd". This should avoid >> using ssh as the transport. I haven't tried this yet. > > Providing you really have a corrupted TCP data stream, that would mean > corrupted backups ... or an rsync protocol failure. I recently experienced a very long battle with this exact problem. A brand new server was being installed using an NFS root which was mounted via TCP NFS. I was seeing random crashes usually related to NFS disk errors and similar. After using wireshark on the NFS server to 'watch' the traffic, I noticed a number of corrupted TCP (NFS) packets arriving. I concluded it was a network issue, and proceeded to replace the network card on the NFS client, the cable, and the switch. I was still seeing the same errors, so I finally gave up and ran a memtest, which found faulty memory. I replaced the memory and it has been stable ever since. Just a suggestion, because again, TCP was not resolving the corrupt packet issue, the packets were getting through to the NFS layer, causing other issues since NFS doesn't seem to handle corrupt packets very well. Regards, Adam - -- Adam Goryachev Website Managers www.websitemanagers.com.au -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFIfBa8GyoxogrTyiURAqlyAJ97SRXB3LF+vBnj2B67fj9qltj98gCgmp1S e0jJMbOztbtbOAIJD8FptuI= =B1GT -----END PGP SIGNATURE----- |