Why degrade and why rebuild?

Hi all,

I am a new guy to use EX4, and I think I did something wrong to my EX4. Today I felt curious to unmount one drive while it is on, and soon a red light was flashing, and the screen shows Vol. 1 is degraded. I think I should not remove the drive unless I turn it off. Then I go to the dashboard and it said I should manually rebuild the Vol.1 and I did. It shows that it requires about 1000 mins to rebuild.

My questions are:

  1. Can I safely remove any drive when I turn them off without rebuilding after I turn them on?

 2. Why do they need to rebuild?

I was trying to find such answers on-line but I could not, hope anyone give me some ideas and Thank you!


In fact, I have one more question: Can I stop rebuilding Vol. 1 without loosing any data?

I am still waiting for the answers, thank you.

Never remove a drive just for the sake of it.

You must now let your unit rebuild the RAID set - while it does so it will not be able to provide the performance - it is “degraded”.  If you stop this process of add/remove other drives, you could lose your complete dataset.

To answer your questions more specifically, you will need to provide information on what sort of RAID you setup your EX4 with.

1 Like

Hello skiwi,

I too am a noob and made a noob mistake.!!! I have the EX4100 and I was cleaining the machine from built up dust and THOUGHT that it’d be okay to open the bay door to clean from inside. Unfortunately, the disk popped out and now I have the same red light and message stating that the raid health is degraded.

My question is: can I safely do a manual rebuild without losing any data? My understanding of a RAID is that since I have 4 drives my data is safe if one drive fails.

Thank you in advance for your feedback

Yes, add the disk back in again, and let the unit rebuild it. You DO have a backup don’t you???