Wifi versus Router Speeds

[dweiss]

A number of routers are now supporting external hard drives with USB 3.0 interfaces. My question is whether that is really worth anything. While, the difference between USB-2 and USB-3 is significant, does it really matter when you are accessing the drive through a wireless router? In other words, since your PC or other device will be accessing the drive over a connection using an 802.11n or, at best, an 802.11ac protocol will the speed of the drive make any difference?

In theory an 802.11n link will connect a device and the router at speeds of up to 150 Mbps (but more likely 54 Mbps) and an 802.11ac link will connect at almost 900 Mbps (maximum), versus optimal USB speeds of: 480 Mbps for USB-2 and 5Gbps for USB -3. Therefore, USB-2 might be a somewhat limiting factor when using an 802.11ac connection but at typical 802.11n speeds it is hard to see what the advantage might be from an upgrade to USB-3.

Am I missing something here?

Thanks,

-Danny.

 

[stevech]

remember that wifi speeds as you mention are the raw bit rates on 802.11.
The IP layer throughput is about 60% of that with an ideal signal strength and no interference.


A USB disk connected to a WiFi routef that supports such is usually constrained by the router's modest CPU coping with the high overhead of the file system on the disk, esp. if its formatted as NTFS rather than a Linux based file system supported by the router.

With a good WiFi signal, the disk speeds will probably be limited not by WiFi, but by the slow CPU in the router burdened with the high software overhead of the file system. NTFS reads on the router USB will be a tiny fraction of what it would be on a PC, and 1/8th of that for disk writes with NTFS.

USB3 is much faster on PCs, but not remarkably so on routers. Perhaps expensive routers with faster CPUs and USB3 can make a difference.

Better to get a 2 drive NAS (Synology or QNAP) unless your use of such a drive is rare and for small files.