To ensure the best performance from an EVO utilizing a 10GbE connection, there are a few settings which should first be enabled on both EVO and the host workstation. Firstly, it is imperative that the maximum transmission unit (MTU) of both EVO and the workstation's 10GbE network card be set to the same value. Though it is generally recommended that the 10GbE port's default MTU of 9000 be used, there is no significant difference in keeping this at the older value of 1500 provided EVO, the workstation, and any switch in-between are set accordingly. To check the MTU currently set for your EVO's Ethernet interface, navigate to the EVO UI's Connectivity pane and scroll to the appropriate 10GbE card. After expanding the 10GbE port's drop-down menu, you should notice something like the following.

As you can see, this EVO currently has an MTU of 9000.

Now, we must verify that the 10GbE card is using an MTU of the same rate. In OS X, this can be done by navigating to the Network pane of System Preferences, clicking the appropriate network connection, then navigating to Advanced and Hardware. There you should find the MTU currently set for your 10GbE card. As of September 2014, a bug in recent versions of OS X requires the Speed option to be set to "autoselect" to achieve an MTU of 9000. If you find that System Preferences is only presenting you with a maximum MTU of 1500, your 10GbE card's drivers may not have been installed properly, or you may have selected the wrong network device.

In Windows, the host configuration's MTU can be verified by finding the appropriate network card in Device Manager, and then clicking Properties. (Some adapters may have their own management utilities/applications.) From this view you should see an option for "Jumbo MTUs." Be sure that if this is set to 9000 on EVO, it is also set in the field indicated here.

No matter which operating system your workstation uses, it is very important that this value match across EVO, all workstations, and all network switches. In the course of troubleshooting our 10GbE technical support incidents we have found that keeping them at different rates has almost invariably led to an erratic or occasionally even an inoperative connection.

Changes made to the MTU speed in EVO will be applied immediately upon saving the page, while changes made to the network interface in both OS X and Windows will require reconnecting to the previously mounted iSCSI or NAS shares.

This article is deprecated!

Please see v2 of the 10GbE recommendations and troubleshooting document.

Given the differences between how 10GbE is implemented by various hardware companies, your card may also require some special "tuning" before it is able to reach the speeds expected for a mature multimedia workflow. In most cases, these options must be set manually. Some 10GbE cards, such as the Solarflare series, offer to include these optimizations with the driver install; others, like those produced by Myricom, involve the editing of a text file. While we will be providing some basic recommendations for these options as they affect 10GbE performance, please keep in mind that manufacturers' recommendations change often, and that the best place to look for hardware-specific performance tweaks remains the release notes to the latest version of your 10GbE card's driver. It is also important to note that optimizing your network card for one protocol, such as iSCSI, may adversely affect the performance of another like AFP. This is why some manufacturers provide their users a selection of drivers to choose from, each with a different intended use case and configuration.

Mac OS X

In Mac OS X, the primary way of applying 10GbE tunings is through the editing of the /etc/sysctl.conf file. All options written to this file are relayed to the kernel, the heart of the operating system, and then applied to the appropriate hardware interface – in this case the 10GbE card. As these settings directly change how the kernel "talks" to the workstation hardware and the local network, it is imperative that they be applied carefully and with the permission of your network administrator.

ATTO 10Gb installers have an option to automatically optimize settings during install, so no tuning may be required.

Taking into consideration manufacturers' recommendations and our own testing, some values that we have found to provide well-balanced results on multiple network cards using OS X versions 10.8+ are the following. Bear in mind that as with any manual kernel tuning, there is the possibility of its becoming outdated in future versions of OS X and your network card's firmware.

kern.ipc.maxsockbuf=16777216

net.inet.tcp.sendspace=4194304

net.inet.tcp.recvspace=4194304

net.inet.tcp.maxseg_unacked=32

net.inet.tcp.delayed_ack=2

Please also note that for those networks relying heavily on SMB sharing, especially when over SMB1, setting net.inet.tcp.delayed_ack to 2 or 0 is especially recommended.

Windows 8.1

As tuning specific settings in the Windows kernel can be somewhat difficult compared to the more streamlined approach of OS X, many 10GbE manufacturers bundle certain optimizations for their cards in the driver install or as part of a special GUI manager. Given the difficulty of altering certain kernel settings in Windows manually, a more in-depth explanation of 10GbE performance tuning is outside of the scope of this article. If you are interested in further configuring your 10GbE interface in Windows, you may find this documentation from Microsoft helpful.

As an added note, we have found that in certain cases disabling Windows Firewall can improve the latency and overall speed of a direct 10GbE-10GbE link. This is due to the increased strain put upon the workstation by having a software filter monitor all incoming and outgoing connections. As with all important network settings, however, you should check with your local system administrator before experimenting with it.

In addition to making sure your network card is properly configured and that your MTU is set to the same value across machines, it is important to make sure that your Ethernet cabling is able to support 10 gigabits of bandwidth over Ethernet. Currently, we recommend Category 6A (CAT6A) or duplex fiber optic cabling be used for all 10GbE network purposes.

More detailed recommendations on cabling and transceivers can be found in our Getting started with SNS products article.

As well as making sure that your workstation and local network are configured properly, there are two more EVO-side options which should be checked to ensure good 10GbE performance over NAS.

If your workflow makes heavy use of SMB and/or AFP, navigate to the EVO web interface's System pane. From there click Advanced, and scroll down to the box reading "NAS Tuning." Please verify that the "Enable SMB2" and "Optimize concurrent NAS operations" (* see note) options are both checked.

In order to more easily determine and consistently achieve maximum throughput over 10GbE, it is recommended that each of your 10GbE workstations be directly connected to one of EVO's 10GbE ports without a network switch in-between. While we understand that network switches are often unavoidable, especially for complex networking environments, the use of a switch does have the potential to both cause issues as well as make issues more difficult to diagnose.

If you have followed all the recommendations in this article and are still experiencing suboptimal 10GbE performance in a switched environment, we strongly recommend temporarily bypassing any switches and attempting a direct connection from the 10GbE card in your workstation to EVO to verify that the problem is not switch-related.