I own a WD MyCloud 3TB in white (don’t know where to see if its gen1 or gen2, cpuinfo says Comcerto 2000 EVM and i got 256MB RAM)
I bought a 3TB USB Drive with USB 3.0. It’s really fast when connected directly to my computer. And it’s also fast when it’s connected to the USB 3.0 Port of my MyCloud and transfer data over the network to this drive (around 80MBytes/s). So the first impression ist good.
But when i create a safepoint to this drive the transfer speed is really slow. Around 10-15MByte/s. And CPU load is about 100%. And the dashboard is very laggy.
I tested a bit over SSH.
Copying a file with rsync, cp or tar is this much slow. Creating a file filled with zeros using dd is much faster, around 80-90Mbyte/s.
I think this is a hardware related issue. If the source and the target are disks directly connected to the mycloud we get this slow performance. If one of this is not directly conncted to the mycloud we get higher performance.
That is GEN1 device.
Slow performance may be due to tiny CPU and low RAM, but I am not sure.
I dont understand why its this much fast over Network and this much slow directly over the local bus. Does this issue still exists in Gen2?
I have to say that my USB HDD is formatted as ext4.
The USB implementation on the MyCloud is rubbish, I’m afraid.
When it is the USB implementation why samba and dd are this much fast? I think the bottleneck is not the USB itself. It is the bus between SATA and USB.
By ‘USB implementation’, I mean “the process of reading and writing data from/to the USB port”. I don’t just mean the physical hardware; I mean the entire chain between USB port and the SATA disk.
Clearly, the MyCloud is capable of reasonable data transfer performance over SMB, which requires the implementation of the SMB protocol, and the SATA interface.
Consider SMB to be the equivalent of USB, and it’s clear that the bottleneck is somewhere in the implementation of the USB protocol stack, USB hardware device driver and USB hardware.
But i’v already saied: Transfer data from my pc over SMB to the USB disk is very fast for me. Above 60Mbyte/s constantly. I can read and write files to the USB disk very fast over SMB. Just transfer from the SATA to the USB (Safepoint, tar, cp, rsync) ist this much slow.
Ah; that’s not something I’ve ever done; the only time I’ve used the USB device, I found it very slow, so I went into the MyCloud linux via SSH, and found the data transfer rate from MyCloud disk to USB disk to be very slow. So I gave up trying to use the USB port at all… Your evidence suggests the USB implementation is perfectly fast enough…
We know SMB:SATA is okay.
We know SMB:USB is okay
So why would SATA:USB be so slow…?
The other point to note is that Safepoint isn’t simply a file copy; it’s having to figure out differences between the two disks. Although an initial Safepoint creation ought to not to need to do that so much…
The other point is that disk speed tests such as Crystal Disk Mark use a number of different file sizes when they do their tests, and the ‘headline figures’ are usually with very large file sizes. I recall at least a 10:1 difference between this bulk rate and the rate for small file transfers.
I know. The safpoint do an rsync. But i tried to copy a large file (6GB) from SATA:USB ober SSH and it’s also slow. I really think the problem is the path where the data goes. I dont know much about bus logic and structures. But i think the problem is located in the bus system. Maybe the AHCI and USB use the same bus or somethink like this. I dont know.