[mirror-admin] Rsync/SSH/Tar file transfers

[Scott Baker]

I thought you guys might find the results of my file transfer test
interesting.

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Here is my real world scenario. I have 15 gigs worth of customer web
data stored on a server. I'll copy it to another server that is
connected to the same GigE ethernet switch. Both machines are SATA (no
fancy SCSI controllers) and have 4 and 8 gigs of ram respectively.

I'm going to copy that data to another server using:

#1) Rsync over SSH

Using dstat while during the transfer I see an average ~100Mb/s of
traffic at any given time. A FAR cry from the full 1000Mb/s they're
connected at. The speed did burst to ~170Mb/s on single large files.

rsync -avP server.com:/huge/web/2011-12-06 /tmp
sent 3101025 bytes  received 15370824277 bytes  13732849.76 bytes/sec

Rsync reports ~109Mb/s average transfer throughput

#2) Raw Rsync

Right away I can see a difference in the transfer speed. Average is
sitting around ~200Mb/s to ~250Mb/s. It bursts up to 400Mb/s on single
large files. Disk is definitely a limiting factor, the transfer is more
bursty.

rsync -avP rsync://backup@server.com/incremental/web/2011-12-06 /tmp

sent 3072973 bytes  received 13688001486 bytes  18291348.64 bytes/sec

~146Mb/s doing raw Rsync. Probably because it's so bursty.

#3) Tar + Netcat

Started out SMOKING fast. The disk write actually peaked ABOVE 1000Mb/s
at the beginning! Transfer isn't as bursty, and it has averaged out
around 90Mb/s. Transferred 15409176735 bytes in 1010 seconds, which is
~122Mb/s.

time tar cf - 2011-12-06/ | nc client.com 7000

In short, rsync using the daemon was the fastest method to transfer
files. Almost 20% faster in fact.

-- 
Scott Baker - Canby Telcom
System Administrator - RHCE - 503.266.8253

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