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Increasing SMB R/W Speed
Hey everyone, I’m just curious if anyone out there has attempted to edit to a shared drive via SMB? The setup I am currently working with has two 2.26 8-core Mac Pros (both 10.6.4), one direct attached via 4GB fiber to a 16-bay, RAID-5 fiber array. The fiber volume is set as a shared folder via File Sharing. Both systems are connected to a Netgear Gigabit Switch.
When I mount the fiber volume via AFP I am able to get about 105-110 MB/s using the AJA System Test. Connecting via SMB results in only 65-70 MB/s using the same test settings.
I know SMB has never been the ideal way to share files between OS X systems. However, given a situation where this is necessary, can anyone suggest a way to bring up the R/W speeds on the SMB shared volume? I’d ideally like to bring it up around that of the AFP share in order to edit video.
Let me know if you need any more information regarding my setup. Thanks.
David Hall
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3 Replies
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OS X uses Samba for its SMB server. There are many docs on the net and at https://www.samba.org on tuning SMB performance. This will require you to edit /etc/smb.conf.
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Thanks Chris. I will look into this. Have you ever gone through the process of modifying the etc/smb.conf file? If so, what were the results? Thanks!
David Hall
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On my Linux and FreeBSD servers I do — that’s generally the way you configure samba. You’ll probably find relatively little specific to tuning on OS X, but should be able to follow, in general, the Linux notes for which there are many.
One of the most common things to adjust are some of the socket options, specifically the send and receive buffers. In the [global] section, you would have:
socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192Other things to look at is tuning your tcp stack. Again, there are a number of articles on the net about this. The best values are something you have to figure out for your specific use. I’m running with 9K jumbo frames (more because I can than I need to) and have these settings in /etc/sysctl.conf on my Mac workstation and using ttcp, I can get close to 900 Mbps (far more than I expected).
kern.ipc.maxsockbuf=500000
net.inet.tcp.sendspace=250000
net.inet.tcp.recvspace=250000
net.inet.tcp.mssdflt=8940Now as you get into this, a couple of notes:
– SMB is not known to be the fastest protocol in the world.
– You’ll want to see if you’re getting limited somewhere else such as CPU or disk. Assuming you tested from the same exact machines with AFP and are now trying SMB, this would give you the same disk IO and network performance leaving CPU as the big thing to watch.
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