High CPU Load on Synology by smbd

Question

I have a Synology DS213j which I access through a VPN via the build-in VPN Server (I use OpenVPN) using Windows Explorer.

Copying files to my local hard drive is very slow in the range of only ~170 KB/s. This seems to be limited by the Synologys CPU which is at 100%. Looking at the ressource monitor in DSM, it shows the smbd process takes >90% of CPU.

The NAS runs DSM version 5.2-5592. The Specs say it has a 1.2 GHz CPU. Shouldn't this be capable of more than this?

I read the DSM 5.2 versions have this kind of issue where they are to heavy-weight for older NASes. Is version 6 better performancewise? Should I downgrade to 4? Or is this not an issue in the OS, and can be solved otherwise? How?

@shodanshok here it is: http://pastebin.com/nmxuD5aQ I replaced the foldernames. — sinned, Jun 04 '16 at 15:24
Thanks. Can you also post the output of `top` during a file transfer? — shodanshok, Jun 04 '16 at 17:28
@shodanshok here it is: http://pastebin.com/cZk0bKj4 Thanks for your interest. — sinned, Jun 04 '16 at 18:42
I'm having the same issue as thread starter. Synology DS216j running DSM 6.0-7321 Update 6 ... smbd goes to 98%, file copy comes to a stand still. Advanced settings like "Enable SMB3" and "transport encryption" Disable don't seem to help. — pcunite, Jun 05 '16 at 03:36
@pcunite: Give a look at my answer, maybe it can help with the high CPU load. — shodanshok, Jun 05 '16 at 09:40
@shodanshok: The share becomes inaccessible from Windows 10 when using max protocol NT1. — pcunite, Jun 05 '16 at 13:08
@pcunite OK, remote the server/client max protocol data; leave only the change notify ones. Does it change anything on the CPU side? — shodanshok, Jun 05 '16 at 14:19
@pcunite For me at least, the share remains accessible from Win10 Pro Build 1511. — sinned, Jun 05 '16 at 15:27

score 6 · Accepted Answer · answered Jun 04 '16 at 20:08

6

First, this seems a common problem with DS213j and DSM 5.1+. Someone reported that after a reboot, the problem went away: have you tried it?

From your top data, it seems that the CPU is busy with system time, ie: doing some syscall. Try changing the following parameters in the smb.conf file and then restart the NAS:

change notify = no
kernel change notify = no
server max protocol = NT1
client max protocol = NT1

Does they change anything?

answered Jun 04 '16 at 20:08

shodanshok

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Adding your changes and restarting the service using `synoservicectl`, the high cpu load has gone away but performance has not improved. Still about 170 KB/s. Most cpu is now taken by `openvpn` (~5%). – sinned Jun 05 '16 at 08:59
1

How much bandwidth did you have? 170 KB/s are about 1.5 MB/s of upload bandwidth which, based on your WAN tech, can be quite good. – shodanshok Jun 05 '16 at 09:19
The router says 1.9 Mbit/s upload bandwidth. This should translate to 237.5 KByte/s. So far, I'm getting ~70% netto performance out of it. I feel like this is probably the bottleneck. Also, I feel quite stupid now. Thanks for your help! – sinned Jun 05 '16 at 09:32
1

Well, at least you solved the high CPU load ;) – shodanshok Jun 05 '16 at 09:39
I guess the `change notify` issues related to high load are related to this bug: https://bugs.freenas.org/issues/4728 – TCB13 Apr 19 '17 at 12:55
In LAN I use to write to this device at >50MB/s through smb. – Marco Aug 19 '17 at 15:19

score 4 · Answer 2 · answered Aug 19 '17 at 12:49

I had also the same problem with :

random slow load problem when I navigate into folder with Windows Explorer
hight CPU usage by the smbd process (~50%) when the random problem that talk about before append
poor speed performance when I transfert file between my Windows computer and my Nas (< 25 MB/s with gigabite connection...)

I solved these 3 problems by simply switching SMB2 to SMB 3 in:

Config Panel > Files services > Win/Mac/NFS panel > Advanced settings in Windows part > Max protocole => Enable SMB 3

I hope these solve your problems too :)

High CPU Load on Synology by smbd

2 Answers2