gerhard911 Posted September 23, 2018 Share Posted September 23, 2018 So, I had just swapped in a 4TB replacement for an aging 3TB drive and rebuilt my 23 drive array. I always rebuild in maintenance mode, so after the rebuild appeared to complete successfully, I shut down unraid (v 6.3.5) and started the array back up. Unraid flagged disk 21 (the one that had just been swapped and rebuilt) as "unmountable", saying it needed to be formatted. I let unraid format the disk (hopefully not a mistake) and now the array is started with valid configuration but no data on disk 21. Why doesn't unraid know that data is missing from that disk and want to rebuild from parity? Did the process of formatting disk 21 cause parity to drop all information for that disk or can I possibly remove that disk from the array, add it back and attempt a data rebuild from parity? TIA for any help or advice. Link to comment
Squid Posted September 23, 2018 Share Posted September 23, 2018 13 minutes ago, gerhard911 said: I let unraid format the disk (hopefully not a mistake) it was Link to comment
itimpi Posted September 23, 2018 Share Posted September 23, 2018 The format command was the mistake (a format is never part of the rebuild process)! When you do a format you are instructing unRAID to create an empty file system on the disk and update parity appropriately. There was probably some sort of corruption at the file system level and the unmountable state could have been corrected by running the appropriate file system recovery tool which would have only taken a few minutes. However you are now past that stage. If you still have the disk you removed intact then the easiest thing to do would be to attach it to the Unraid server and mount it using the Unassigned Devices plugin so that you can copy its data back to the new disk. Alternatively copy the data back using your backups (assuming you have them). Link to comment
gerhard911 Posted September 23, 2018 Author Share Posted September 23, 2018 I do still have the original 3TB drive but no free SATA port to attach it to. If I swap it back in as disk 21, I believe using the New Configuration tool will rebuild parity from data on all 23 disks. Is that correct? Link to comment
itimpi Posted September 23, 2018 Share Posted September 23, 2018 2 hours ago, gerhard911 said: I do still have the original 3TB drive but no free SATA port to attach it to. If I swap it back in as disk 21, I believe using the New Configuration tool will rebuild parity from data on all 23 disks. Is that correct? Yes - you could do that. The New Config invalidates parity so it will need rebuilding, and after that you could repeat the rebuild process. if you have no free SATA ports I would instead use a SATA->USB adapter/case or dock to attach the old drive via a USB port and then copy files from it that way. Although USB is not recommended for array drives it is perfectly satisfactory (and convenient) for drives you only want attached to the system temporarily. It is also a convenient way to attach drives that are purely for backup. Link to comment
gerhard911 Posted September 23, 2018 Author Share Posted September 23, 2018 Thanks for confirming my understanding of the New Configuration tool. I have parity rebuilding now with the original disk 21. Unfortunately that will take ~ a day and a half. I also appreciate the SATA / USB docking station suggestion. My experience with those units, however has been poor. I have owned and used several, from multiple brands. Every single one eventually failed, some quite quickly. I suspected some cheap common chipset or other component was used in them all and gave up on the whole concept. I should put in a single port external SATA controller card so I can attach an external drive bay for such purpose in the future. Thanks again for your help itimpi ! Link to comment
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