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What might limit data transfer rate to NAS?

What might limit data transfer rate to NAS?

I have two NAS (Buffalo Linkstation Pro, WD MyBook World), which are connected to 2 PCs with a Gigabit LAN connection. All devices are in "Gigabit mode", meaning all show that their connection speed is really 1 GBit. But the transfer rates to and from the NAS drives are very low, on average 5 MByte/sec, copying large files with several GByte in size.

Asked by: Guest | Views: 46
Total answers/comments: 2
Guest [Entry]

The WD MyBook World is CPU-bound or disk-controller-bound. If you do an online search for the throughput of the first versions of MBW, you will find that 5MB/s is quite common. There is nothing you can do about this.
Guest [Entry]

"I wouldn't worry too much about Jumbo Frames if the maximum possible speed is in the order of 30MB/s.

First thing to check is that the NAS is not doing anything else (other transfers, other actions) at the same time, because home NASes typically have severely limited processor capacity.

It also depends heavily of the source and target of the transfer... the slowest link in the chain sets the top speed... so if you move files between the two NASes, then the overall speed will be that of whichever is the slowest NAS.

Most modern harddisks should be able to do 50-60MB/s easily, but... if you put an older 'spare' harddisk in one of your devices this could very well also be limiting the maximum speed.

I would not imagine that the computer that is doing the transfer is likely to be the bottleneck, but if you bring up the process manager you can have a look at the CPU and network graphs and see if either of those is peaking at the time... it could easily be that the network port on your PC is maxed out with other traffic meaning that there is only 5MB/s left.

Based on the 5MB/s I'd almost have assumed that maybe the port on the PC (the middleman) is a 100Mbit port, because that'd make sense... 100Mbit = approx 10MB/s, but since the PC might be copying from one NAS to another, that means half the bandwidth is available for each connection."