Just noticed that the CPU on both units is jumping between 80% and 99% utilisation. The remote EX4 is the one running the highest though. I wonder if this is the limiting factor to throughput.
Why the CPU is being so heavily used to simply copy data is a mystery though.
The files being copier are all large data files. Anything between 4GB and 50GB each. Around 75% of the roughly 1000 files in this share will be 4-5GB in size. The files will not change once the copy is complete but will be added to over time.
After 42 hours it has done 1TB. That is an appaling rate on a gigabit network. I’m looking at 15 days for this to complete. And whilst that isn’t a huge problem as it is a one-off backup copy, I worry about what 15 days of constant disk access and high CPU will do to the devices longevity. That said, the devices are running at normal temperatures and fans are not running high, so it isn’t generating much heat.
As a further note, all 8 disks across the two units are all 7200RPM WD Black 4TB disks.
Would throughput be quicker I wonder if I used a computer to initiate the copy and act as middle-man?
Well, the most important and relevant questions are - what kind of files are they and how many files. You have answered the latter - which gives an idea that it’s not a small number but the really important question is then, what types of files are these. Are they media files like videos or music. If so, then that’s the issue. Anytime you copy media files over to the EX2/EX4/Mirror, there are couple different processes that run - wdmcserver and wdphotodbmerger, that index the media files and prep any pics/videos to be shared by the cloud app. Unfortunately, the reality with a lot of NASes out there, including many by Synology and QNAP, two of the leading vendors, suffer from the same issues that WD’s NASes suffer - a weak CPU that is overwhelmed by the processing power required to handle CPU-intensive tasks. So contrary to sgallant04’s claim that just stepping up to a Synology NAS would resolve your issues, I would say that only if you move to a Synology with a non-Marvell CPU but one with an Intel Atom CPU or better. But those higher end CPUs are on NASes that are also much higher priced. If you instead bought a Synology DS414slim which comes with a Marvell Armada 370 chip, you’d be no better off than you are with an EX4 NAS. Also, keep in mind, WD does sell Intell Atom-powered NASes under their business-class Sentinel NAS series, which would give you much better performance at a much higher price point - just like moving to a non-Marvell Synology model would.
The fact remains that performance-wise the cheaper NASes proliferating the market today, whether from Synology or WD or somebody else, will have these slowness issues when it comes to processing media files. And I know you would say, well, I am merely copying the files and not processing or transcoding them, but because majority of folks want to share these media files on the cloud, these processes are mandatorily run on all media files.
You can do a couple things that might help the situation just a bit but not much - you can turn off Media steaming and iTunes music streaming during this time of copying files. That will turn a couple processes like twonkyserver, etc. off…which will give a very small relief to the CPU…but with a weak CPU you just aren’t going to be able to do as much as with a more powerful CPU on a pricier NAS.