Slow FTP transfer speeds...

[robegan99]

Hi,

I have two FreeBSD 8.2 servers, both using Intel Pro/1000 NICs and connected to the same GigE switch (source machine has the file stored on a RAID0 volume made up of 12 x 3TB SAS drives, destination server is writing the file to a single 3TB SAS drive, no RAID). I have users who move large files (150GB or so) between these servers, and they complain of slow transfer speeds using FTP (i.e. a 150GB file taking 3 hours to be transferred, or roughly 14 Mbps). I used iperf between the two servers and it measured 842 Mbits/sec for bandwidth between the two servers. I think the issue is related to disk I/O but I don't know a good way to go take measurements and verify that. Can anybody suggest a way to predict how fast the transfer rate between two servers should be using FTP?

 

[throAU]

That would depend on how busy the remote server is - but you could maybe test the drive in it with bonnie++?

It does sound a bit slow to me though - thinking out loud here - I'm not sure if FTP is optimised for larger packet sizes to get better throughput (I'd suspect it is brain-damaged like the rest of the protocol) - are you able to test transfer speed using something like SCP or HTTP instead?

Also - how busy is the switch? Bear in mind that consumer-grade switches may not be able to run all ports at line-rate at the same time... a 24 port "gigabit" switch for example may only have a 3-4 gigabit backplane to share between all ports...


Once you've got an estimate of disk throughput with bonnie++, you should have an idea whether or not you're chasing a disk throughput or network/protocol throughput problem.

 

[wblock@]

I have users who move large files (150GB or so) between these servers, and they complain of slow transfer speeds using FTP (i.e. a 150GB file taking 3 hours to be transferred, or roughly 14 Mbps).

14 MBps, if my math is right (megaBytes, not megabits).