Hi everyone,
I am hoping someone can help me out with some advice regarding my NSA325 (armv5) NAS running Arch Linux ARM.
This NAS has two drive bays. One has an SSD drive in it (off which Arch is running), the other has a HDD in it.
Whatever I try, I can't seem to get any kind of decent file transfer speed over the network out of this NAS. Maybe it is more of a sysadmin question, but hopefully someone has an idea how I could start to debug this.
Setup:
- NAS -> Cat 5e -> TP-Link Gbit switch -> Cat 5e -> Laptop
Experiments:
- Network speed test over this link, using iperf, yields 680Mbit/s (not quite a full Gbit, but not too shabby either)
- dd a large file from HDD to /dev/null, inside the NAS: 117MB/s
- dd a large file from HDD to SSD, inside the NAS: 58.5MB/s (same result using cp)
- scp the same large file from HDD on NAS to the laptop: Maximum speed of 12.6MB/s.
- scp the same large file from SSD on NAS to the laptop: Maximum speed of 11MB/s
- Using netcat: same result.
- EDIT: doing "ssh LAPTOP 'cat /tmp/largefile' > /dev/null" from the NAS (pulling large file toward it from laptop) also doesn't yield faster speeds. I guess this takes the disk performance out of the equation.
- EDIT 2: just found out iperf has a file input mode. Using iperf -c -f from the NAS to transfer the same large file to the laptop.... 235Mbit/sec. Maybe this has something to do with the network protocol used?
- EDIT 3: also tested some loopback network speeds. iperf through the loopback interface on NAS reaches about 1.5Gbits/s. Transfering a file, using cat over SSH, through the loopback interface on NAS reaches only about 5MB/s, even when piping the output to /dev/null.
- EDIT 4: also tested without the switch in-between. Same result.
I don't understand why the transfer is so slow here. Users of this NAS on the stock firmware, and also users who flashed Debian onto it, report speeds of ~60MB/s. The iperf test and hard drive tests separately suggest that much more than 12.6MB/s should be possible.
Does anyone have any ideas? Thanks in any case.