NAS - Slow transfer rates

Possible reasons and troubleshooting steps for slow transfer rates to, and from a NAS device.

Here are a few reasons why a NAS device might seem to be transferring more slowly than expected:
  • NAS devices will not transfer data as fast as a direct connected device will, such as an external USB or eSATA drive. Typical data transfer speeds range from 3MB/s to 20MB/s for consumer level NAS devices. (**This applies more to older LaCie NAS devices, newer generations are capable of higher speeds when connected to Gigabit rated networks**)
  • It's important to understand that NAS devices are in actuality little computers. They include an Operating System, RAM, a CPU and even a little motherboard. They have to process the data transferred to them over the network. Any transfer between two computers requires resources from both the destination (NAS) and source (Computer) and the transfer will only go as fast as the slowest device. 
  • Additionally, the same can be applied to the network's infrastructure as a whole. If you have a 10/100 network or even a 1000 network with a 10/100 device: the entire network will transfer at the speed of the slowest device. 


For further troubleshooting steps, please see the check list below: 

  • Each transfer to a NAS device counts as a connection to that NAS and divides its processing abilities. Every NAS has a specific amount of capacity for the transfers and every connection will divide that capacity. To ensure the fastest transfer possible, only have one computer connected and transferring only one data stream at a time. 
  • Be sure that only routers or switches are used throughout the network and that no hubs exist in the infrastructure. Hubs do not have the ability to multi-path connections and will slow the network down. 
  • If a lot of small files are being transferred, that will be considerably slower than transferring larger files. This is due to the computing power required to scan and close many individual files rather than one file. (The same difference in transfer speed can be seen when transferring large or small files from a computer to direct attached storage device.)
  • Sometimes the OS calculator does not give a reliable reading. Try bench-marking the drive to verify these speeds are correct. Many free benchmark tools are available online. 
  • As the NAS has a limited amount of resources to transfer a file; so too does your PC. If you're experiencing slow speeds, it may be the computer used and not the NAS.