The NAS should have Log for you to check the IP from where.

Copy paste the IP in google and see where it from.

Last time got such experience before. Whole day for whole month kena hack. After I comeback from China.

And guess what, the IP is from China. 

I don't think it's the NAS that detect bad sector. The HDD itself that detect it and inform the OS. The HDD also will do marking on the map table that the sector cannot be used anymore. What's the ID number and attribute from S.M.A.R.T info?

You can try hook the HDD to PC and check for any error or bad sector using program such as CrystalDiskInfo.
Firstly, you need to understand what is DNS and DNS Server. From Cloudflare site:


DNS Server is the one that manage DNS. It will periodically connect with other server to update the ip address for url.

Pi-hole mostly used for DNS server. Do you change your DNS server to use Google's 8.8.8.8 or Cloudflare's 1.1.1.1?
The reason to use other DNS server instead of default ISP is for bypassing blocked site or security purpose.
Now more people are using pi-hole instead because the DNS list also include list of url to block, such as harmful site url or advertising url.
Usually you will install adblock on every computer browser or phone, but if the router is configured to use pi-hole for DNS, all the devices that use the router connection will be filtered by pi-hole.

Jdownloader is usually used for direct download. Some download site limit your ip can only download 1 time then have to wait how many hours/day. JDwonloader if configured, can make your router disconnect from isp and then connect back to get different ip. It also block cookie and change it's id so that the download site can't identified you, unlike internet browser. Jdownloader also can be used to download youtube video/audio/subtitle.

Edit: added the bold

Bad SATA cable or connector also can cause communication error thus report it as bad sector. It's more usually happen to cable as can easily damage or low build quality cable. Try to clean the connector slot.

1 new drive and then 2 RMA drive, all end with bad sector? Is the HDD for usage in NAS? You could try getting HDD from different brand to eliminate the possibility the RMA HDD is problematic. But I feel most likely communication error due to damage or dirty connector.

First thing you should do is make a backup of your data, if you don't have it. Doing rebuilding put a lot of stress on the remaining HDD and if another HDD died all the data will be gone. This is assuming you are using RAID5 or SHR.

recertified/refurbished drive don't hv red labels if not mistaken

I think you should get a new drive that you buy from store (or borrow a drive that you know is good, or maybe just swap the slots - to confirm this is a drive issue or slot issue).

'Recertified' means the drive are most likely RMA'ed drives but went through a short retest at vendor site to map out the bad sectors or to temporarily 'fix' the original errors (sometimes just by resetting the SMART logs) and then sent to another customer who RMA, hopefully this customer won't see the issue or the drive manage to run/survive until after warranty period is over before the error comes out again.

recertified/refurbished drive don't hv red labels if not mistaken

I also got RMA 1 WD HDD last time, sticker write as RED but it's not red colour sticker.
After use about 1 year the drive died.

Sorry, I actually meant you go and buy a new drive, not ask for replacement from the shop or use a RMA drive since an array rebuild (but I'm not sure what scrubbing does) usually involve a lot of read and write from the drives in the array and these 'recertified' drives could be just working well enough to pass but might not last long. The intense read/write during array rebuild will stress/cause these 'recertified'/'walking wounded' drives to fail prematurely.

I hope you find out what's causing the failures.

I upgraded to DSM7 2 months ago. I got write here some feedback.
https://forum.lowyat.net/index.php?showtopi...ost&p=101511491

Possible. The second disk have Current Pending Sector. See after the number decrease if it will operate back as normal.
https://kb.acronis.com/content/9133

Multi-Zone Error Rate also could be indicative there's something wrong with the surface or read/write heads. If you have redundancy, can just left it like that and see if it fix itself. If no then backup your data.
https://kb.acronis.com/content/9136