Hi Randy The WIRE speed of a 10bT NIC is approximately 1 MB / Second The WIRE speed of a 100bT NIC is approximately 10 MB / Second The WIRE speed of a 1000bT NIC is approximately 100 MB / Second In reality, you can get all of 1MB / Second in 10bT You can get, (IF YOU PUSH HARD) about 6.5MB /Second in 100bT You can get, (IF YOU PUSH REALLY HARD) about 37 MB Second in 1000bT. You can change some of that by changing your packet size some. If, however, you go to JUMBO FRAMES you can essentially double your bandwidth in 1000bT. One caveat. If you go to JUMBO frames (packets), the interface you set for them, won't see/hear any other interface NOT speaking with the same size frame. Thus, if you switch to JUMBO frames, you may lose regular network connectivity (unless, of course, you use one NIC for backups/etc, and one for other purposes) Much of the loss in performance as you scale is based on the fact that the operating system is involved in packet assembly and disassembly. This is why TCP/IP Offload Engines are becoming popular in NICS (aka TOE cards) See Alacritech and Intel and Adaptec for further details. Also, as is obvious, you're likely going to get WAY better performance across NFS or (god help you) SAMBA, than you will over SSH, due to encryption taking up lots of bandwidth. Ted Letofsky Linux Newbie Otherwise geek. -----Original Message----- From: tclug-list-bounces at mn-linux.org [mailto:tclug-list-bounces at mn-linux.org] On Behalf Of Randy Clarksean Sent: Wednesday, July 06, 2005 10:29 AM To: tclug Subject: [tclug-list] Data Transfer Speeds - LAN I have a number of systems wired locally with switches and hubs. I would like to be able to do more backups from these systems to a stand alone backup system with a couple of large hard drives. The issue then becomes data transfer speeds because a couple of these systems have 100-200 GB of data stored on them. The typical data transfer speeds have been on the order of 2-3 MB/sec when all network cards are 10/100 MB NICs. There are a number of online resources listed below on how to "tune" one's machines to get faster data transfers. Has anyone out there "tuned" their LAN in order to get decent data transfer speeds? Do these suggested changes truly move the transfer speeds up drastically? I realize there will be collisions, etc. ... but I would guess that I SHOULD be able to get transfer rates up to 25-50 MB/sec. Does that seem reasonable? Or ... would I get better data transfer rates by mounting the drives with NFS on a Linux box and copying everything via NFS over TCP? Any of your experiences would be greatly appreciated. Many thanks in advance. http://rdweb.cns.vt.edu/public/notes/win2k-tcpip.htm http://support.microsoft.com/kb/169789/ http://www.psc.edu/networking/projects/tcptune/#Linux ... or NFS related information ... http://nfs.sourceforge.net/nfs-howto/performance.html ... for gigabit networks .... http://datatag.web.cern.ch/datatag/howto/tcp.html Randy _______________________________________________ TCLUG Mailing List - Minneapolis/St. Paul, Minnesota tclug-list at mn-linux.org http://mailman.mn-linux.org/mailman/listinfo/tclug-list