How can storage system handle different write streams at the same place?

Normally, if two applications send two write requests to the same place (lba) of the disk, applications or file systems will add lock for it, so only one request will be handled at a time.

But now there is a difficult problem. There may be multiple write requests that should be written to the same place, but applications don't handle the lock. There is no file system, because the data are directly written to the raw disk. What I can do is to modify the code of the storage system. Things are very complicated now. Suppose there are two requests, A and B. Then finally the data in the corresponding lba may be one of the three results:

1. All data are from A.
2. All data are from B.
3. Parts of data are from 开发者_运维知识库A; parts of data are from B.

In my opinion, result 1 & 2 are acceptable, but result 3 is not acceptable. But someone doesn't think so. How about you opinions?

I agree that it should be all of one or none of either. This can be done quite easily by using a form of storage system manager, and writing to the manager in large enough chunks. The manager can do appropriate locking internally so that only one block from one request is written at a time, and you don't get overlaps.