>The 4 bytes of the CRC will probably be all right
>
>But this has nothing to do with the OS. Other hashing methods (MD5, SHA-*) should all calculate the same independent of OS
>You could even use a block cipher and only store the last block as the hash

They are all ok. But, since I based my CRC32 calculation based on the file size, where the file size is not different because we moved to a new OS, this is why I have this issue. So, assuming no matter the method I would have taken, it would have given a new value in the new OS.

>To calculate a hash you have to read the whole file. Whether that file contains sparse storage or not has no influence. The file size will be the same but the number of bytes stored on disk (depending on sparse or not) may differ

That is interesting. Because, in that case, CRC32 would be affected. The hash wouldn't. Thanks for the info

In your experience, if calculating a hash longer to execute than a CRC32? If yes, does this increase based on the file size?