Rsync over SSH - (40MB/s over 1GB NICs)

Documentation.md

The fastest remote directory rsync over ssh archival I can muster (40MB/s over 1gb NICs)

This creates an archive that does the following:

rsync (Everyone seems to like -z, but it is much slower for me)

• a: archive mode - rescursive, preserves owner, preserves permissions, preserves modification times, preserves group, copies symlinks as symlinks, preserves device files.
• H: preserves hard-links
• A: preserves ACLs
• X: preserves extended attributes
• x: don't cross file-system boundaries
• v: increase verbosity
• --numeric-ds: don't map uid/gid values by user/group name
• --delete: delete extraneous files from dest dirs (differential clean-up during sync)
• --progress: show progress during transfer

ssh

• T: turn off pseudo-tty to decrease cpu load on destination.
• c arcfour: use the weakest but fastest SSH encryption. Must specify "Ciphers arcfour" in sshd_config on destination.
• o Compression=no: Turn off SSH compression.
• x: turn off X forwarding if it is on by default.

Original

rsync -aHAXxv --numeric-ids --delete --progress -e "ssh -T -c arcfour -o Compression=no -x" user@<source>:<source_dir> <dest_dir>

Flip

rsync -aHAXxv --numeric-ids --delete --progress -e "ssh -T -c arcfour -o Compression=no -x" [source_dir] [dest_host:/dest_dir]

SSHrsync.sh

rsync -aHAXxv --numeric-ids --delete --progress -e "ssh -T -c arcfour -o Compression=no -x" user@<source>:<source_dir> <dest_dir>

I benchmarked this a little bit with 1GB of random data, modern software (Fedora 30) on a CPU that does NOT have AES acceleration. Test data:

dd if=/dev/urandom of=/tmp/1g bs=1M count=1024

rsync default settings -> 22.71MB/s

rsync -P /tmp/1g 127.0.0.1:/tmp/1g.2

disably tty allocation -> 20.39MB/s

rsync -P /tmp/1g -e "ssh -T" 127.0.0.1:/tmp/1g.2

disable compression -> 193.42MB/s

rsync -P /tmp/1g -e "ssh -o Compression=no" 127.0.0.1:/tmp/1g.2

scp -> 109.9MB/s

scp -o Compression=no /tmp/1g 127.0.0.1:/tmp/1g.2

Conclusion

Disable compression, but don't bother with arcfour, even without AES acceleration you'll be faster that gigabit ethernet. Disabling tty allocation had no effect in my testing. Scp is significantly slower than rsync.

Running ssh -v SERVER you'll what cipher is used:

debug1: kex: server->client cipher: [email protected] MAC: <implicit> compression: none
debug1: kex: client->server cipher: [email protected] MAC: <implicit> compression: none

So we are using aes256-gcm, which fortunately is the same cipher that gocryptfs uses, so we can look at this benchmark table: https://github.com/rfjakob/gocryptfs/wiki/CPU-Benchmarks . You should basically get >100MB/s on any x86 CPU younger than 10 years.

3fr/3g2/3gp/3gpp/7z/aac/ace/amr/apk/appx/appxbundle/arc/arj/arw/asf/avi/bz2/cab/cr2/crypt[5678]/dat/dcr/deb/dmg/drc/ear/erf/flac/flv/gif/gpg/gz/iiq/iso/jar/jp2/jpeg/jpg/k25/kdc/lz/lzma/lzo/m4[apv]/mef/mkv/mos/mov/mp[34]/mpeg/mp[gv]/msi/nef/oga/ogg/ogv/opus/orf/pef/png/qt/rar/rpm/rw2/rzip/s7z/sfx/sr2/srf/svgz/t[gb]z/tlz/txz/vob/wim/wma/wmv/xz/zip

Added some more extensions to that list:

3fr/3g2/3gp/3gpp/7z/aac/ace/amr/apk/appx/appxbundle/arc/arj/arw/asf/avi/bz/bz2/cab/cr2/crypt[5678]/dat/dcr/deb/dmg/drc/ear/erf/flac/flv/gif/gpg/gz/iiq/jar/jp2/jpeg/jpg/h26[45]/k25/kdc/kgb/lha/lz/lzma/lzo/lzx/m4[apv]/mef/mkv/mos/mov/mp[34]/mpeg/mp[gv]/msi/nef/oga/ogg/ogv/opus/orf/pak/pef/png/qt/rar/r[0-9][0-9]/rz/rpm/rw2/rzip/sfark/sfx/s7z/sr2/srf/svgz/t[gb]z/tlz/txz/vob/wim/wma/wmv/xz/zip

I benchmarked this a little bit with 1GB of random data

On random data compression can't help. However, if you have text files and a slow connection, it is a logical choice.

zst is also worth adding

SSH_ARGS="-T -o -c [email protected] Compression=no -x"

you have a typo here, that should be like this:

SSH_ARGS="-T -c [email protected] -o Compression=no -x"

Saw not much movement in the variations here when testing across 2 ec2 instances on AWS in 2 different AZs. I ended up using this which includes most of what I could gleam as optimizations but the speed fluctuated enough among with and without that your mileage will definitely vary as well.

$ rsync -aHAxv --numeric-ids --delete -P -e "ssh -T -c [email protected] -o Compression=no -x" 500MB.file 10.16.87.187:~

Regarding the suggested -T, there is no TTY allocation by default when SSH runs a comand on the host vs running a shell. It's redundant. On some systems (Debian 9 and later, maybe some earlier), you can do -c none which is ideal if you care about speed and not privacy.

i have done a small up-to-date ssh test using several cipher, between 2 AWS r5.12xlarge and got this:

[email protected]        190.89MB/s  (default if not option used)
aes128-ctr                           259.01MB/s
[email protected]               339.05MB/s
[email protected]               298.20MB/s
none                                 189.72MB/s

i didn't test arcfour, but in previous tests, it was faster... but as require changing the sshd server to support that cipher, i'm trying to avoid it
interesting is the aes256-gcm is faster than the aes128-gcm, probably because of optimization and hardware support. the cipher none, while it do not return error, seems to fallback to the default, so anyone saying that -c none will disable encryption probably do not know that its really using the default cipher! :)

No other ciphers were tested as current ssh only have those as default enabled ciphers

To all.

I'd like to know how to place '--exclude /backup/somedir' in the string because it doesn't work. Thanks in advance.

To exclude a directory("<source_dir>/bigDir") you need to put the name of directory in current directory like this example :
rsync -aHAXxv --numeric-ids --delete --progress --exclude 'bigDir' -e "ssh -T -c [email protected] -o Compression=no -x" user@:<source_dir> <dest_dir>

for a Mac to Linux transfer it's useful to use other options. Arcfour is not available for most new machines anymore and UTF-8 on OS X is different than UTF-8 on Linux (important if you have Umlauts like Germans, Samba/NFS will fail otherwise). My command if both (Mac & Linux) machines support AES on their processors and you want to transfer from Mac to Linux:

rsync -rltv --progress --human-readable --delete --iconv=utf-8-mac,utf-8 -e 'ssh -T -c [email protected] -o Compression=no -x' <local_mac_source> <remote_linux_dest>

reverse the iconv option if you want to transfer from Linux to Mac.

how would you do mac to mac?

Not recommended, I almost trashed my entire movies collection by doing this, good thing I canceled it.

This was such a great post to find!
I was set to leave my transfer going at 5-10MB/s but couldn't go to sleep with 1.2TB going for 30hours!
(This was also from Synology NAS to MacOS)

As others mentioned early on in this post using specific SSH options can affect the transfer rate dramatically: -e "ssh -T -c aes128-ctr -o Compression=no -x". Primarily the Compression factor. I couldn't see notable differences and didn't test more than comparing to "-c [email protected]" but got variably up to 50-90MB/sec.

DO use --dry-run and --itemize-changes which is a great record of what is actually going to happen.
Always be careful of SOURCE and DESTINATION.
Pause and think, before setting things in motion!

If you want a little help managing a collection of commands you run and an environment conducive to setting up rsync command lines you could try (on a Mac) RsyncOSX as a GUI front end (although I still prefer to run the actual command in a standalone terminal.)

@L1so > Not recommended, I almost trashed my entire movies collection by doing this, good thing I canceled it.

Don't paste everything you see on the internet without looking the flags up first /shrugs

To decide which cipher is the best, I recommend using this script to benchmark for yourself: https://gist.github.com/joeharr4/c7599c52f9fad9e53f62e9c8ae690e6b

dunno, dunno

git, tons of settings tried. 100gb+ repos. Millions of files, etc of content. Just for bench purposes (not working dirs). But results pretty sad on internal network on Vultr.

strange - i'm only getting 27-30MB/s with rsync -aHAxv --numeric-ids --progress -e "ssh -T -c [email protected] -o Compression=no -x"
transferring a 1.6TB file between two Epyc servers with plenty of resources and 10GB networking. i get 500MB/s transferring video files from my desktop to my storage server. not sure what's up here.

update: it increased to 52 MB/s, which is... definitely not as fast as I would like, but it's fine.

Not recommended, I almost trashed my entire movies collection by doing this, good thing I canceled it.

🤡

I'm not sure if people are still interested in this, but if you don't care about encryption then tar + netcat is by far the quickest way to transfer directories:

destination:
nc -l -p 7777 | tar -xpf -

source:
tar -cf - sourceDir/ | nc [dest ip] 7777

throw in 'pv' to see xfer speed.

Oh rad! I’ll try this today! Appreciate that.

…

On Sun, Sep 11, 2022 at 8:49 AM ip-rw ***@***.***> wrote: ***@***.**** commented on this gist. ------------------------------ I'm not sure if people are still interested in this, but if you don't care about encryption then tar + netcat is by far the quickest way to transfer directories: destination: nc -l -p 7777 | tar -xpf - source: tar -cf - sourceDir/ | nc [dest ip] 7777 throw in 'pv' to see xfer speed. — Reply to this email directly, view it on GitHub <https://gist.github.com/4393116#gistcomment-4297214>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AA7LWR3KKCZOMWXXKDNWFZTV5XPOLANCNFSM4HMITOZA> . You are receiving this because you commented.Message ID: ***@***.***>

Great discussion.

I found this to be the best option. "ssh -T -c [email protected] -o Compression=no -x" .Probably aes256 was faster than arcfour due to hardware optimizations or something. Also might play with/without rsync -z based on the quantity/size of the files to transfer. No compression was faster for an already compressed single big tar.gz file

https://gbe0.com/posts/linux/server/benchmark-ssh-ciphers/

That’s a great report , thanks!

…

On Tue, Sep 27, 2022 at 12:37 AM Akhil Jalagam ***@***.***> wrote: ***@***.**** commented on this gist. ------------------------------ https://gbe0.com/posts/linux/server/benchmark-ssh-ciphers/ — Reply to this email directly, view it on GitHub <https://gist.github.com/4393116#gistcomment-4316545>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AA7LWR5ZYQVG4JQ4NPS57PDWAKBYXANCNFSM4HMITOZA> . You are receiving this because you commented.Message ID: ***@***.***>

To not let this stand as is, some facts: compression is off by default in ssh (and always has been in openssh), tty allocation is off when used in rsync and x forwarding does not affect bulk bandwidth in any way. Any difference in speed measured is not due to these options, but more likely because of a bad test setup, such as first making tests with cold disk cache and the with hot cache. The only change that can affect speed is the cipher (and not turning compression explicitly on in rsync or ssh).