Forum Discussion

Sensei - Experienced User

Sep 04, 2017

EDA500 on RN516 - Scrub very slow

This problem has been previously reported by another user on an earlier version of the OS: ReadyNAS-516-2x-EDA500-Scrub-on-EDA500-very-slow. It persists in OS6.7.5. As scheduled, my main data vo...

Guru - Experienced User

Sep 23, 2017

dbreiny1 wrote:

This is a problem with the EDA500 and I am not sure why I was unable to get a response from mdgm-ntgr, StephenB or someone else within Netgear.

I don't work for Netgear, and I don't own an EDA500. I didn't see much I could do to help resolve your issue, so I didn't chime in.

Sandshark

Sensei - Experienced User

Oct 25, 2017

And still no response from anyone at Netgear. If I run a scub on the volume on my EDA500 from SSH (btrfs scrub start /eda1), it runs 50X faster than if I run it from the GUI. That's comparable with the speed on the main array. Note that I am not using the -B option to not background the task. So what in the world is the GUI doing wrong when it starts a scrub, either scheduled or manually?

mdgm-ntgr
NETGEAR Employee Retired
Oct 26, 2017
Scrubbing from the GUI involves more than just doing a scrub at the filesystem level.
- Sandshark
  Sensei - Experienced User
  Oct 26, 2017
  Can you be more specific as to what it is doing if not just a BTRFS-level volume scrub? btrfs scrub status /eda1 returned data consistent with the progress bar in the GUI when I initiated the scrub via the GUI. In fact, the scrub I started with SSH also shows up in the GUI, progressing at the much accelerated pace. It's going a tad slower than the main volume -- I estimate it'll take about 18 to 20 hours -- but that's acceptable. The speed of the GUI-initiated scrub is not.
  
  And even if it's doing something more, why does the scrub of my 14.5TB RDA500 volume take 54 days compared to 18 hours for my 27.3TB main volume? I assume that scrubbing the main volume is also doing that something more. Scrubbing the main volume uses about 50% of the CPU time -- enough to slow other processes some. Scrubbing the EDA500 via the GUI takes almost none. Scrubbing via SSH command takes about the same amount as the main volume scrub. Whatever causes that lack of CPU usage certainly seems like the probable root cause to me.
  - NETGEAR_Team
    Community Manager
    Oct 27, 2017
    Sandshark I've escalated this and requested a more detailed response for you. Feel free to PM me if you don't receive a response within the next couple of days and I'll follow up.