With a gigabit network interface, jumbo frame support, high speed SATA drives and a healthy amount of system memory, the Duo has the hardware to read and write data over a high speed network quickly. Jumbo frames are disabled by default, but can be enabled via a check box in the Network menu, then a system reboot.
Netgear's menu (Figure 16) cautions that selecting the Jumbo Frame option requires an Ethernet switch and clients that support Jumbo Frames. This is important, as enabling Jumbo Frames on a network without end to end Jumbo Frame capability isn't beneficial. For general networking details on Jumbo Frames, take a look here.
Figure 16: Jumbo frame enable
The Netgear manual states that the Duo supports jumbo frames up to 7936 bytes (8K). I tested this with the jumbo frames option enabled on a Linksys SRW2008 switch and a client PC running XP Pro with an Intel NIC configured to support 9014 byte jumbo frames.
A ping test from my XP Pro PC with the -f and -l options, shown in Figure 17, shows the Duo (192.168.3.170) responding to echo frames up to 7926 bytes.
Figure 17: Jumbo frame ping test
Enabling jumbo frames doesn't always translate to improved performance, however. For example, I copied a folder with 4 GB of digital pictures from the Duo to the PC (i.e. reading) with jumbo frames enabled on Duo, NIC and switch and it took about 15 minutes. Interestingly, running the same copy operation with Jumbo frames disabled was slightly faster, taking only 13.5 minutes.
But copying a single large file—a 3.5GB Linux Image— showed improvement with jumbo frames enabled. In this case, the file copy took just 2:50 minutes with jumbo frames enabled and 3:25 minutes with jumbo frames disabled. To net it out, the ReadyNAS Duo definitely supports jumbo frames transmissions, which can be beneficial for some data transfers.
In addition to enabling jumbo frames as applicable, Netgear has some performance guidelines for the Duo on their ReadyNAS product site. Netgear recommends disabling the “journaling option...to boost write performance by about 25%,” but only if a UPS is connected to the Duo. The journaling option is used to ensure data parity in a RAID configuration. Without a UPS and journaling disabled, you run the risk of data corruption in the event of power failure.
Additional Duo performance tweaks are available under the System > Performance menu. Choices include Optimizing for OS X, Enable fast CIFS writes, and Enable fast USB disk writes as shown in Figure 18. Some of these tweaks may be applicable to your network.