rsync and zfs send slow, copy from Windows laptop fast ?!

[leenux_tux]

Hello Forum,

Got a really odd issue I wanted to share to see if anyone has seen this before or has any pointers as to where the issue might be. A little background first.

• I have two FreeNAS systems
• FREENAS01 is my "main" server, used for storing laptop backups, music, movies, Clonezilla images, software ISO's and as an iSCSI target for a separate VMWare ESXi box.
• FREENAS02 is used purely for backups of the main system.
• All systems are wired ethernet (1GB)
• All systems are connected via a switch (not a hub)
• Both FREENAS boxes have 8GB or RAM

I have never really taken much notice of file transfer speed as when I use rsync to transfer changes to FREENAS02 from FREENAS01 I just set the task off and let it run, however, today I figured I would have a play with ZFS SEND and set off a zfs send job to copy a snapshot of my iSCSI target from FREENAS01 to FREENAS02 and was surprised at how slow it was, which started me doing some more testing...

• Copying a 512MB file from my laptop to either FREENAS01 or FREENAS02 , I get 60MB/s + (sometimes 80MB).
• Copying a 512MB file the other way (from FREENAS01 or 02) back to my laptop I get very fast transfer speeds as well, around 65/70MB/s
• Rsync shows an average MB/s of around 6MB/s between FREENAS01 and FREENAS02
• Using "systat -ifstat 1" on both systems whilst the ZFS SEND is running shows an average of around 10MB/s outbound from FREENAS01 with the same inbound on FREENAS02.

Now this has really surprised me. I would have thought that (rightly or wrongly?) that the slower of the two types of transfer would be CIFS, not "standard" FREENAS ??

Has anyone else seen similar network speeds whilst doing rsync or zfs send data transfers ?

Thanks

:)

 

[cyberjock]

Rsync is very CPU heavy, and single threaded. Expecting high performance on an Atom with rsync is expecting too much. Not sure abou ZFS SEND and RECEIVE as I haven't tested CPU loading extensively, but it is at least multi-threaded.