How to Quickly Transfer data off Extremely Slow ReadyNAS NV+

Hi Everyone,

I am helping out a family friend that has been running a small business for the last few years with a ReadyNAS NV+ 4-drive storage for all of their work files. In the last couple of weeks, accessing it became extremely slow from their computers, so much so that whenever they would access a folder, they would be forced to go and make a cup of tea. Throughout the day the NAS shared volume would also unmount from the computer randomly. 

I am pretty tech savvy but don't have a lot of experience with these things. Any help is appreciated.

I logged into the frontview and it was extremely slow to operate. I'm not sure what it should be, to be honest, but it was at least a minute to load each page in here. I first had a look at the drive health and all appeared to be OK as they were all green. Looking closely at each drive there were a few errors that were reported in the Smart status of the 4th drive, indicating to me that this is likely the cuprit. It's a RAID5 setup, so I understood (could be wrong) that it should still be operating if one drive appeared to be faulty. In saying that, it was saying that regardless of the errors, the drive is operating. Glancing at the logs for the past few weeks as well we can see that there was a "failure event" for drive 4 about when this issue started. 

We discussed everything and decided that Google Drive would be a better solution for them to store their 200GB or so lot of files, so I got to work trying to get what I could off the NAS to put up there. 

I started by copying and pasting in Finder (they use Macs exclusively - AFP) but the drive kept "disconnecting" through the incredibly slow transfer.

Then I tried a terminal (cmd) CP: command to get the stuff over and this failed as well with an "invalid directory" message and it just stopped. 

I think tried adding an external hard drive to one of the USB ports on the NAS, formatting it using the frontend (FAT32) and then starting a backup through the NAS frontend to get stuff transferred. After nearly 24 hours only 3GB has transferred and another "invalid directory" has caused me not to be able to complete this operation either. I tried connecting to the USB share on the NAS through AFP in Finder and it was also incredibly slow, which got me thinking:

If it's slow on the USB connected drive as well, it may not by the Hard drives in the NAS, but the NAS OS or something similar that's the issue.

I have already pinged the NAS and it's healthy, so it doesn't indicate network issues (left this running for ages and no issues to be seen). Also updated to the latest firmware (this took about an hour too) but the same issue remained. Obviously have restarted it over and over and same issue. 

The business used a offsite backup tool called spider oak as well, but it appears that this hadn't been functiioning correctly with its scheduled backups for a couple of years. Not a great situation to be in.

So here's my question:

What is the best way to get the data off this NAS as quickly as possible, considering everything above? Should I replace the 4th drive first and go from there? Best way to go about this?

Raid5 | RAIDiator 4.1.14

ReadyNAS NV+

4xWD500GB hard drives

Please and thankyou everyone. We're in a real pickle.

Tim