I'm using DD over Netcat to copy a hard disk from one system to another, straight clone.
I booted RIP on each system.
target system: nc -l -p 9000 |pv|dd of=/dev/hda source system: dd if=/dev/hda |pv|nc 9000 -q 10
The transfer seems to be hovering around 10 or 11 MB/s, with bursts near 18 registering. The two systems are connected to a gigabit switch. Ethtool eth0 on both is showing:
Settings for eth0: Supported ports: [ TP ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Full Supports auto-negotiation: Yes Advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Full Advertised auto-negotiation: Yes Speed: 1000Mb/s Duplex: Full Port: Twisted Pair PHYAD: 0 Transceiver: internal Auto-negotiation: on Supports Wake-on: umbg Wake-on: g Current message level: 0x00000007 (7) Link detected: yes
I think I may be confusing some numbers for the transfer rates, but is this an expected speed for transferring the data?
EDIT: I just tried using two different cables that are marked as 5e compliant, and used a crossover connector to link the two systems directly. While ethtool still says they're set to a speed of 1000Mb/s, the transfer rate appears to be only slightly higher than before. Either the drives are sucktacular, the network cards are crud, or the processor must be bottlenecking, I'm guessing.
EDIT2 I just tried taking a second hard disk from a unit that needs to be cloned to and physically connecting it to the master clone. Originally one IDE channel went to a HD and another went to the CD-ROM. I took the master's hard disk and connected it to the same channel as the CD-ROM, so they should be /dev/hda and /dev/hdb. I took the cable that was on the CD and connected it to the "blank slate", so it should be /dev/hdc.
I rebooted and ran "dd if=/dev/hda|pv|dd of=/dev/hdc", and I'm getting a whopping...10 MB/s. It's fluctuating wildly between 8 MB/s and spiking to 12.
So...I'm thinking it is the hard disks that are giving crap performance...I'm just so used to network being a bottleneck that it's weird for me to think of disks as being the problem!