I have a QNAP TS451U that has 11 year old 6GB disks that are near full. They are in a 4 disk raid 5 array. I hate changing disks due to high risk during the process, but I wanted to be ahead of any failures. I brought 4 x new 10GB NAS rated WD drives and started the one by one update process. I set the resync speed to priority to minimise the downgraded risk window and could just accepted a slow network for a while. The first drive rebuilt ok, but with the second drive things went south.
I woke up to a red flashing power light and no network response. I thought maybe all the activity has triggered the classic LPC failure so I powered it down and connected a scope to the LPC port to check and powered it up. The clock and frame signals looked fine and it booted up. After about a day it completed rebuilding the raid array and then did a file system check. At the end of it DataVol1 was stuck as read only. For some directories I see “cannot access Structure needs cleaning”. It df reports “/dev/mapper/cachedev1 16.1T 16.0E 2.7P 4274566335% /share/CACHEDEV1_DATA” which I find worrying.
I assume it is because the drive is near full, but as it is read only there no way to remove files. So I have switched to my backup NAS to get my servers and workstations back online until I can fix the read only and structure needs cleaning errors etc.
To fix the read only problem I found this post Volume Read Only "SOLUTION" - QNAP NAS Community Forum which has the risky steps “Remove Disk” and “Plug in the Hard Disk while ssh into the box/Hot Insert” etc. I am wondering if, in my case there may be a better solution. I assume the read only limit won’t stop me completing the one by one disk replacement process on the remaining two drives and then I could expand the raid array size. It is a simple raid array, not thick or thin setup.
Would that work? Would it automatically become writable? Would the cleaning complete? All suggestions welcomed.