How do I maximize LAN speeds using Gigabit Ethernet, jumbo frames?

Question

I move a lot of large files (RAW photos, music and video) around my internal network, and I'm trying to squeeze out the fastest transfer speeds possible. My question has to do both with decisions about hardware and what settings to use once it's all hooked up.
This is what I have so far:
-- imac 3.06GHz, macbook pro 2.53GHz
-- Cisco gigabit smart switch capable of jumbo frames
-- Buffalo Terastation Duo NAS (network attached storage), also capable of Gbit and jumbo frames
-- All wired up with either cat6 or cat53e.
-- The sizes of the files I'm moving would include large #s of files at either 15MB (photos), 7MB (music), 1-2GB (video) and 650MB (also video).
-- jumbo frames have been enabled in the settings of the macs, the switch and the buffalo HD.
-- I've played with various settings of simultaneous connections (more of a help with smaller files), no real difference
-- Network utility shows the ethernet set to Gbit, with no errors or collisions.
-- have tried both ftp and the finder's drap and drop
-- also, whenever I'm doing a major move of data, I kick my family off the network, so there is no other traffic that should be interfering.
Even with all that, I'm still lucky to get transfer speeds at 15-20mbps, but more commonly at around 10. The other odd thing I've encountered while trying to up my speeds, is that I might start out a transfer at maybe 60mbps, it will maintain that for about 30-60sec and then it appears to ramp itself down, sometimes to as low as 1-5mbps. I'm starting to think my network is mocking me
I also have a dual band (2.4/5) wireless n router (not jumbo frame capable), but I'm assuming wired is going to trump wireless? (NOTE: in my tests, I have disabled wireless to force the connection through the ethernet).
Can anyone help with suggestions, and/or suggest a strong networking reference book with emphasis on mac? I'm willing to invest in additional equipment within reason.
Thanks in advance!
juliana

Answer 1

I'm going to pick and choose to answer just a few of the items you have listed. Hopefully others will address other items.
• This setup was getting me speeds as high as 10-15MB/sec, and as low as 5-6MB/sec when I was transferring video files around 1-2 GB in size
I would think a single large file would get the best sustained transfer rates, as you have less create new file overhead on the destination device. It is disturbing that the large files transfer at a slower rate.
• Would a RAID0 config get me faster write speeds than RAID1? I have another NAS that can do other RAID configs, which is fastest as far as write times?
RAID0 (Striped) is generally faster, as the I/O is spread across 2 disks.
RAID1 is mirrored, so you can not free the buffer until the same data is on BOTH disks. The disks are NOT going to be in rotational sync, so at least one of the disks will have to wait longer for the write sectors to move under the write heads.
But RAID1 gives you redundency. RAID0 has not redundency. And you can NOT switch back and forth between the 2 without reformatting your disks, so if you choose RAID0, you do not get redundency unless you provide your own via a backup device for your NAS.
• what is the most efficient transfer protocol? ftp? smb? something else? And am I better off invoking the protocol from the terminal, or is the overhead of an app-based client negligible?
Test the different transfers using a large file (100's of MB or a GB sized file would be good as a test file).
I've had good file transfers with AFP file sharing, but not knowing anything about your NAS, I do not know if it supports AFP, and if it does, whether it is a good implementation.
If your NAS supports ssh, then I would try scp instead of ftp. scp is like using cp only it works over the network.
If your NAS support rsync, that would be even better, as it has the ability to just copy files that are either NOT on the destination or update files which have changed, but leave the matching files alone.
This would help in situations where you cannot copy everything all at once.
But no matter what you choose, you should measure your performance so you choose something that is good enough.
• If a client is fine, does anyone have a suggestion as to best one for speed? Doesn't have to be free -- I don't mind supporting good software.
Again just test what you have.
• Whats a good number to allow for simultaneous connections, given the number of files and their size?
If the bottleneck is the NAS, then adding more I/O that will force the disk heads to move away from the current file being written will just slow things down.
But try 2 connections and measure your performance. If it gets better, then maybe the NAS is not the bottleneck.
• What question am I not asking?
You should try using another system as a test destination device in the network setup to see if it gets better, worse, or the same throughput as the NAS. You need to see about changing things in your setup to isolate where the problem might be.
Also do not rule out bad ethernet cables, so switch them out as well. For example, there was a time I tried to use Gigabit ethernet, but could only get 100BaseT. I even purchased a new gigabit switch, thinking the 1st was just not up to the task. It turned out I had a cheap ethernet cable that only had 4 wires instead of 8 and was not capable of gigabit speeds. An ethernet cable that has a broken wire or connector could exhibit similar performance issues.
So change anything and everything in your setup, one item at a time and use the same test so you have a pear to pear comparision.