Running bitcoind -reindex-chainstate one could see in the debug.log:
2020-07-07T11:22:08Z Leaving block file 96: CBlockFileInfo(blocks=534, size=134102608, heights=271294...272192, time=2013-11-24...2013-11-29)
2020-07-07T11:22:09Z Pre-allocating up to position 0x1000000 in blk00097.dat
2020-07-07T11:22:09Z Pre-allocating up to position 0x100000 in rev00097.dat
Is file pre-allocation required if *.dat files are not corrupted?
Hi, I don't see the issue here. See BlockManager::FindBlockPos. You have the "Leaving block file" message which means that it was a newly processed block. In adding this new block, the code noticed that blk file 96 would go over its 128 MiB size limit, so it finalized file 96 and went to new file 97. Part of that normal process is allocating the new file in 16 MiB chunks. This in itself has nothing to do with corruption. If you think there is some corruption involved, then there must be more context not mentioned in this issue.
Guess this can be re-opened if there is anything further to discuss.