Slow transfer from NSA325 NAS

[SanderV]

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.

[summers]

Tried a few machines here.

First I worked from /tmp - as my usual file system in compressed, and would confuse the issue. First file was created:
$this->bbcode_second_pass_code('', 'dd if=/dev/urandom of=/tmp/text.bin count=2048 bs=65535')
First copied across a usb ethernet interface to my pocket beagle:
$this->bbcode_second_pass_code('', '[summers@pocketbeagle ~]$ scp 192.168.7.17:/tmp/text.bin /dev/null
summers@192.168.7.17's password:
text.bin 100% 128MB 4.0MB/s 00:32
')
Then did the same from the router which is directly connected to the nas via ethernet:
$this->bbcode_second_pass_code('', 'root@DavidSummers:~# scp summers@192.168.2.144:/tmp/text.bin /dev/null
summers@192.168.2.144's password:
text.bin 100% 128MB 1.4MB/s 01:32')
And finally on an odroid-c2, so armv8 with more grunt than the other machines, connected via ethernet to the router:
$this->bbcode_second_pass_code('', '[summers@odroid-c2 ~]$ scp summers@192.168.2.144:/tmp/text.bin /dev/null
summers@192.168.2.144's password:
text.bin 100% 128MB 10.7MB/s 00:11')
So whats clear is that the processing load of ssh makes a big difference, the router (with a runt processor) was slowest by a long way. The odroid-c2 which went via the router - was 7 or so times faster.

So my guess is that its processing load that is limiting things.

[SanderV]

Thanks for expermenting along! And good to see I'm not the only one.

Indeed the CPU is at 100% during all of these transfers.

Still, I feel like more should be possible, based on reports of other people reaching read speeds of ~60MB/s - I've seen such reports from people running the stock NAS firmware, but also from people running Debian or Arch ARM.

I will try to boot Debian from USB to see if that would make a difference.

[Kabbone]

did they use encrypted transfers? Perhaps try with normal samba or NFS

[Sheika]

lol