Hello folks!
I’ve got two PR4100:s sitting on my desk. One 56TB and one 16TB. I use the smaller one to backup some of the shares from the larger one each night - through ‘Remote Backups’ app jobs. I’ve noticed that the speed isn’t really up there. The same thing goes when I SSH into the larger one and copy files to the other one. In general, a scp session to copy one large file between the two sits at around 27 MB/s (more like 200Mbit/s). I’ve got both PR4100 connected to a Unifi 48-port Gbit switch using two cables each, link aggregated in the switch and on the network settings of the PR4100:s I’m using 802.3ad. This, if I’m not mistaken, gives me 2x1Gbit where one client in theory could get (almost) 1Gbit and if there are two clients accessing the NAS at the same time, the whole bond could be used with (in theory) a total of 2Gbit/s.
Each disk (WD RED:s) is capable of delivering almost 180-200MB/s and in a RAID5 setup it should be even more I think.
Do anyone have any thoughts about this. Why do I not see numbers like 80MB/s instead? Is there any limitations in transfer rates over the network when I connect through SSH and copying files like that. If I copying the large file from and to itself, with cp it’s of course as quick as I can exspect but as soon as I involve network, the speed drops down to around 27MB/s.
Example with one large .zip file (9GB)
-
cp
Copy the file to itself from SSH shell takes 37 seconds. (Read 9GB and write 9GB) -
scp (local)
If if copy the file from-and-to the same PR4100 (scp [filename] sshd@localhost:[destfile]) it takes over 5 minutes with a speed of around 27MB/s
I get the same speed if I do the same scp test but instead copying the file to the remote PR4100.
I’m kind of stuck here I must say. I’ve tried to back down from link aggregation on the switch and also put the PR4100:s in ‘Adaptive Load Balacing’ without any progress. Max speed is still the same. All connections are reported as 1Gbit. If I do ‘ip a’ on both PR4100:s I see that the network config is (from what I can see) correct. It’s a bond of both interfaces:
2: egiga0: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master bond0 state UP group default qlen 1000
link/ether 00:14:ee:03:95:bb brd ff:ff:ff:ff:ff:ff
3: egiga1: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master bond0 state UP group default qlen 1000
link/ether 00:14:ee:03:95:bb brd ff:ff:ff:ff:ff:ff
10: bond0: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether 00:14:ee:03:95:bb brd ff:ff:ff:ff:ff:ff
inet 172.16.1.5/16 brd 172.16.255.255 scope global bond0
valid_lft forever preferred_lft forever
Any ideas of what I can try to do to get higher speed? Anyone else who uses link aggregation together with PR4100 or any other dual UTP NAS?
Thanks is advance
// Robert