No matter if normal format or quick format, in the end the file system is initialized. This means it writes a root block in the middle of the partition and marks it invalid. Next time the partition is mounted (usually immediately after format) the disk-validator jumps in and builds the bitmap. The bitmap is built in memory and then written to disk. After that the root block is marked valid.
If there is not enough memory, the disk-validator silently fails and leaves the root block invalid.
In any case the "invalid" flag is shown as "validating" in the info list, no matter if validation is still running or already failed.
In OS 3.2 the validator has been improved to throw an error message when it fails. But lack of memory still inhibits validation.
