Advice on improving the SMB transfer rate?

Daisuke

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Jun 23, 2011
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I have a Dell C2100 setup similar to @Mirfster's with 192GB RAM and 12 2TB Seagate Constellation disks. SMB shares are enabled with no customizations. I mounted a /media directory on my Mac did a quick read test through a CAT6 cable on a 5GB file located on the NAS, reading at 106MB/s:
Code:
$ time dd if=media/file.mkv of=/dev/null bs=8k
590138+1 records in
590138+1 records out
4834417009 bytes transferred in 45.579273 secs (106066128 bytes/sec)

real    0m45.796s
user    0m0.275s
sys    0m5.864s


When I transfer a file from NAS to my Mac, the speed is half:
Code:
$ rsync -a --progress --stats --human-readable media/file.mkv .
building file list ...
1 file to consider
file.mkv
       4.83G 100%   53.29MB/s    0:01:26 (xfer#1, to-check=0/1)

Number of files: 1
Number of files transferred: 1
Total file size: 4.83G bytes
Total transferred file size: 4.83G bytes
Literal data: 4.83G bytes
Matched data: 0 bytes
File list size: 74
File list generation time: 0.005 seconds
File list transfer time: 0.000 seconds
Total bytes sent: 4.84G
Total bytes received: 42

sent 4.84G bytes  received 42 bytes  55.90M bytes/sec
total size is 4.83G  speedup is 1.00


From your perspective, is this considered acceptable? I would like to get close to 90MB/sec transfer speed, if possible.
 
Last edited:
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I think you can do better, but im not sure where to tell you to start. Is this a wired connection and not wifi right?
 

Tony-1971

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You can also check local write speed of your Mac to understand which is the best write speed you can reach
 
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I do no optimizations at all and max out about 111MB/s. Ive seen these speed reductions as a result of really long runs and or interference. Can any machines on your network saturate the GB link?
 
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Ok, my thought is you can try a few things. Set static IP on your mac and connect directly from mac nic to your TN nic and run an iperf test both ways taking the router out of the mix once. See how speeds compare.

My second thought is to try different cables wherever possible. Cabling has caused problems like this for me in the past on several occasions.
 

Tony-1971

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Also you can try using cp instead of rsync. To see how much time cp command consume there is time command in linux (not sure if also present in Mac OS).
 

Daisuke

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Also you can try using cp instead of rsync. To see how much time cp command consume there is time command in linux (not sure if also present in Mac OS).
Copy matches the same time I get when I do a read file, that means I get a decent transfer speed at 105MB/s. Am I interpreting this right? Is strange that rsync is so slow. media/file.mkv is the file located on my NAS.
Code:
$ time dd if=media/file.mkv of=/dev/null bs=8k
590138+1 records in
590138+1 records out
4834417009 bytes transferred in 45.579273 secs (106066128 bytes/sec)

real    0m45.796s
user    0m0.275s
sys    0m5.864s

$ time cp media/file.mkv .

real    0m45.672s
user    0m0.008s
sys    0m7.685s
 
Last edited:

Tony-1971

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