Guillaume LaurentIs it normal for a LaCie 2big dock to take several days to rebuild its RAID 1 array following the replacement of a failed disk ?
Turns out it was because the volumes were still mounted, and one of the partitions was used by Time Machine. Once this was disabled, rebuilding was over in a few hours.
The next frustrating part came when I discovered there was no way to resize the partitions I had on the 2big RAID array (one APFS for file storage and one old MacOS Journaled for Time Machine) to use the available 2TB (because the 6TB HDs have been replaced by 8TB ones). I had to completely re-partition the HD and am currently restoring from backup.
Said backup was also surprisingly hard to perform, as I did it on a Synology NAS, and neither cp -pR nor rsync -a are able to properly preserve the file dates in that case. As the Finder will keel over at copying so many files (2TB in total), the only tool I could find to do it correctly was Transmit from Panic Software.