gigabit switches

[redhatgeek]

has anyone used the gigabit over copper switches yet?

i have a linksys 5 port gigabit switch and I am not very happy with the performance

i maintain 2 mirrored rsync/ftp servers on rsyncs to the interent the other syncs localy across my gigabit network

both servers were running fedora core 1 although currently i'm in the process of upgrading the one to FC2

i only get about 25 megabytes a second transfer rate i should be getting around 100 Megabytes a second right?

two differant network cards 1 32bit intel gigabit and 1 32bit netgear gigabit

[Jman]

What kind of hard drive is in these servers? Individual drives can't supply data at 100 MB/s sustained. You are getting 200 Mbit/s, more than I ever got over 100 Mbit ethernet.

[Varkk]

Also don't forget that the Gigabit net can nearly saturate all PCI bandwidth so if any of the machines have other PCI devices active that will slow it down. I think most motheroard architectures have the IDE on the PCI bus as well so that is a major issue with using the PCI 1000mbit cards. Basically to get true gigabit performance you need to system t be able to backup the card.

[redhatgeek]

both servers are almost identical both have

MSI k7d motherboard and both are scsi

one is a dual 2800 and one is a dual 2400

[belthezar]

I agree, 25MB per second is hella fast over the network. I bet you are slowed down by your hard drive. unless you are using RAID with multiple drives your not going to get much over 25 or 30 MB/sec sustained.

As an example, I have a P4 2Ghz workstation running FC2 with a 7200 RPM IDE drive.

here is my hdparm -t /dev/hda output

[root@avod-sandej-lx mnt]# /sbin/hdparm -t /dev/hda

/dev/hda:
Timing buffered disk reads: 128 MB in 3.03 seconds = 42.25 MB/sec

I'm peaking at 45 MB/sec just inside the box getting to the hard drive. Throw in going over the NIC as well and I bet I would peak around what you are getting with gigabit networking.

Try running that hdparm test on your drives and see what the max performance your drive is even capable of and you might begin to feel better about your network speed. Heck, your connection between systems is faster then most peoples directly connected hard drives!

[redhatgeek]

/dev/sda:
Timing buffer-cache reads: 808 MB in 2.00 seconds = 404.00 MB/sec
Timing buffered disk reads: 124 MB in 3.04 seconds = 40.79 MB/sec

/dev/sdb:
Timing buffer-cache reads: 740 MB in 2.00 seconds = 370.00 MB/sec
Timing buffered disk reads: 122 MB in 3.00 seconds = 40.67 MB/sec

/dev/sdc:
Timing buffer-cache reads: 744 MB in 2.00 seconds = 372.00 MB/sec
Timing buffered disk reads: 92 MB in 3.06 seconds = 30.07 MB/sec

[redhatgeek]

maybe i would get better performance setting up a RAID 0

[belthezar]

well that is definitely what is "slowing" you down. (if you can call it slow!) What are the results on your other system? I assume this is the system that is receiving the data, but the sender's specs are important too.

Setting up a RAID 0 using two drives theoretically would double performance, however you may get closer to choking your PCI bus as mentioned above. If you have nothing better to do, it's certainly worth tinkering around with! Remember you will need to do a RAID 0 on both computers, as if you only beef up one system you will still be limited by the other.

Really gigabit networking is still quite a ways ahead of most of the rest of the computer. There are of course servers and such that are able to handle the connections, but for the average home user they will never reach the maximums offered by gigabit until hardware specs increase quite a bit.

[Varkk]

I remember going to a LAN and the guy next to me had a i875 based motherboard which has the CSA architecture. (Basically the onboard giga lan runs off this new CSA bus as does the onboard IDE RAID 0 array so these are not bottlenecked by the limited PCI bandwidth.) He was at one stage uploading at about 80-90 mb/sec. This was uploading several files up to about 10 people each with 100mbit cards. I think when he was uploading to another guy on a a similar setup he was getting 75mb/sec. Another guy who had a PCI giga-lan card would notcie a definate slowdown whenver he played music on his PC due to the sharing of PCI bandwidth between the IDE controller, NIC and soundcard.