On 07/12/15 14:17, David Raison wrote:
>> A 'parallel' ssh
>> would not necessarily do the same thing where session timeouts are
>> involved.  Might be worth snooping with tcpdump/wireshark at both ends
>> to see if they both end up waiting or if something has sent a reset.
> 
> I'll see what I can do. Since it is transferring quite a lot of data
> before timing it out, I set up tcpdump to limit itself to 96 bytes.
> Otherwise this would fill up the disk quite quickly.
> 
> ~# tcpdump -v -s96 -i tun2 port rsync and host 10.21.32.5 -w
> pcap/client.pcap

So I still collected some 4.4 GB of caps, split them into chunks of 10
mio each and this is what I can see:

The last ACK from the backup server to the client:

81873   144.097589      10.8.80.6       10.21.32.5      TCP     52      33331 → 
873 [ACK] Seq=1
Ack=73045447 Win=1321 Len=0 TSval=1701819479 TSecr=193052428

Then a series of Spurious Retransmissions from the client to the Server:

81874   172.857945      10.21.32.5      10.8.80.6       RSYNC   1406    [TCP 
ZeroWindow] [TCP
Spurious Retransmission] Server MOTD

Followed by several Dup ACK from the server to the client:

81875   172.857979      10.8.80.6       10.21.32.5      TCP     64      [TCP 
Dup ACK 81873#1] 33331
→ 873 [ACK] Seq=1 Ack=73045447 Win=1321 Len=0 TSval=1701826669
TSecr=193052428 SLE=73003473 SRE=73004827

And finally the client sends a reset:

81884   172.862230      10.21.32.5      10.8.80.6       TCP     40      873 → 
33331 [RST, ACK]
Seq=73004827 Ack=1 Win=0 Len=0

Now, I'm not an expert at reading TCP streams, so I'd be grateful if
anyone could point out what I need to be looking for, or how to
interpret this data.

Looks like the Windows client is ending the connection, but does anyone
see why from this?


> The backup process is always starting with /cygdrive/c so at least some
> of these files should be "same".

I can't tell what happened, but this time around (with rsyncd, not
ssh+rsync) I'm seeing "same" on the second attempt.

Also, it managed to get more files this time around than at any previous
attempt, so it created a new partial backup.


Best regards,
David

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