I faced an issue with one of my PR4100s, that I had not experienced before.
After a necessary Hard reboot, due to the NAS spending a few days in ‘powering down mode’ with no hope of actually powering down. The Drive 3 LED went red and the Dashboard informed me that the drive was Bad.
I had a replacement HD Red 8TB at hand and substituted it with the faulty one.
Once the System started to rebuild the RAID 5, it stopped after ten minutes and this time showed Drive 1 and 2 as Bad with the corresponding red LED drive lights.
This of course freaked me out, as now I had in effect three Bad drives! So I replaced the original ‘Bad’ Drive 3 and rebooted. This time Drive 1 and 2 were OK and three was Bad, as expected. Am currently transferring all data to another NAS as quickly as I can, but the experience has got me stumped!
All the drives in My Cloud PR4100 are configured under RAID 5. If you remove drive-3 from enclosure, remaining drives 1 & 2 will go to red due to RAID mismatch. Once you place the defective drive-3 with the new one and rebuild RAID from the dashboard, it will come back online with blue status.
Thank you for your reply and input. Much appreciated.
I did try again to replace the Failed Disk 3, But I get the same result once the system is up. Drives 1 & 2 show as bad, failing the S.M.A.R.T. test. Which stops me from being able to rebuild the RAID.
Disk1|Failed - Quick disk test failed. Please backup your data and replace this disk. If you need further assistance, contact WD Support.|
|Disk2|Failed - Quick disk test failed. Please backup your data and replace this disk. If you need further assistance, contact WD Support.|
|Disk3|Passed - Quick disk test completed successfully.|
|Disk4|Passed - Quick disk test completed successfully.|
Reinserting the Bad Disk 3, makes the Raid come back up , with volume degraded warning and instruction to replace Disk 3.
Disk1|Passed - Quick disk test completed successfully.|
|Disk2|Passed - Quick disk test completed successfully.|
|Disk3|Failed - Quick disk test failed. Please backup your data and replace this disk. If you need further assistance, contact WD Support.|
|Disk4|Passed - Quick disk test completed successfully.|
Bit of a head scratcher. I wonder if I should format the new Disk prior to inserting?
Two questions. First: is your replacement HDD brand-new, or used? If used, I would format if I could.
Second: is the replacement HDD the same size as any of the other three? My understanding, in dealing with RAID 5, is:
When replacing a bad disk, always–always–replace it with a disk of the same size. Technically it could go larger, but I always select a disk of exactly the same size.
When upgrading to a larger total capacity by using larger HDDs, engage the “Change RAID Mode” routine, select the option for up-sizing the array, and follow the on-screen instructions to the letter.
I also have to keep remembering: when the system says it’s busy, you wait.
Now I hate to mention this, but I start to wonder: could it be that replacing one failing disk with a new one, uncovered a failing condition in each of the other two? If so, your course of action of transferring all your data to another NAS could be your only course. Then you’ll have to decide: if you want to keep the other NAS around for any reason, rebuild the whole thing from start to finish. Get yourself at least two more drives, shove them in, and engage the routine for configuring it as RAID 5 de novo. Just consider that NAS dead and in need of near-total replacement.
I have had this issue happen to me TWICE. Single failed drive only to have the rebuild fail again when a new drive was installed. The LUN is showing healthy and that the volume was damaged on the unit’s webpage. Each time I get a failed drive, I’ve had to offload my data and reformat the whole unit.
I’ve given up using RAID 5 set of four drives and decided to go with a RAID 5 with three drives with the fourth drive being a hot spare. I hope this will fare better for the next drive failure.
