If RAID degraded how should I do?

If we created RAID 5 from HDD1, 2, 3 & 4, but system warning about RAID degraded, please check following steps:

1. Check from NAS ADMIN WEB page -> STORAGE -> RAID MANAGEMENT page, to check which HDD out of RAID. The "DISKS USED" file would show which RAID HDD existed in the RAID, as like number "1, 2, 3" means HDD1 HDD2 & HDD3 existed the RAID.

2. From item 0 know it is a RAID5 volume form HDD1~4, but "RAID MANAGEMENT"-> "DISKS USED" know HDD1~3 exited but HDD4 out of RAID.

3. We need check this HDD health status first, check from NAS ADMIN WEB page -> STORAGE -> DISK INFORMATION.

3-1. If HDD4 missing, perhaps this HDD is damaged, here recommend replace a health HDD join back to RAID. (Thecus provide HDD only; if you need HDD RMA service please consult where you purchase this HDD or HDD manufacturer directly.)

3-2. If HDD4 show on the screen, please click to choose HDD4 and check SMART icon to check HDD health status, normally the "Reallocated Sector Count" "Current Pending Sector" & "End-to-End error" should be 0. (Check the HDD SMART is enough and you have no necessary to do "DETECT BAD BLOCK" or "BAD BLOCK SCAN") We recommend replace HDD if above 3 item not stay at 0, because a health HDD should have no this value, once any number occurred means HDD have something wrong and should going to worst in the further. (Each HDD have difference reability, we STRONG recommend choose enterprise HDD)

3-3. If HDD4 show on the screen, please click to choose HDD4 and check SMART icon to check HDD health status, and "Reallocated Sector Count" "Current Pending Sector" & "End-to-End error" stay at 0, means HDD should be health, perhaps someone shaking, loosen or remove this HDD, after check installation and we could add this HDD back to RAID.

4. If went to add HDD into a DEGRADED RAID, please check from NAS ADMIN WEB page -> STORAGE -> RAID MANAGEMENT page -> Choose the RAID volume -> EDIT -> check the "SPARE" or "HOT SPARE" box which HDD you went join into RAID volume for rebuilding -> APPLY for RAID rebuilding. During RAID rebuilding NAS and HDD would be busy and response slow, even we could access NAS for some basic file IO, but it is NOT recommended doing this. Here recommend choose holiday or non-business hour for RAID rebuilding. Also please configure EMAIL NOTIFICATION before and don't stay at RAID MANAGEMENT page, in reason this page would check RAID status every few second, thus EMAIL notification would mail to you while RAID rebuild completed.

*Note1: If you can't get EMAIL notification or test mail from GMAIL, please check following FAQ:

http://thecus.kayako.com/default_import/Knowledgebase/Article/View/580/0/why-my-nas-cant-accept-gmail-as-email-notification-account

or

https://support.google.com/accounts/answer/6010255