If you buffer to disk, the same problem will eventually show up. Queues (in memory, on disk, anywhere) are all ultimately bounded, and when they are full, you have 2 choices: block or drop. Somehow you need to make the choice, there's no getting away from it.
If you don't make the choice consciously, say by assuming that you can buffer to disk and avoid the problem, at some point you'll fill up your disks and your system will block: you'll have unknowingly picked the "block" option. If you decide to rotate logs and delete old rotations when too many logs are present, then you're picking the "drop" option...
