'jfr disassemble --max-chunks N' command always puts N + 1 chunks to the first output file if the recording consists of more than N chunks.
For example, the attached jfr recording chunks.jfr consists of 5 chunks.
$ jfr disassemble --max-chunks 1 chunks.jfr
Examining recording chunks.jfr ...
File consists of 5 chunks. The recording will be split into 4 files
Writing chunks_0.jfr ... 459384
Writing chunks_1.jfr ... 219049
Writing chunks_2.jfr ... 237447
Writing chunks_3.jfr ... 218449
$ jfr summary chunks_0.jfr
Version: 2.1
Chunks: 2
...
For example, the attached jfr recording chunks.jfr consists of 5 chunks.
$ jfr disassemble --max-chunks 1 chunks.jfr
Examining recording chunks.jfr ...
File consists of 5 chunks. The recording will be split into 4 files
Writing chunks_0.jfr ... 459384
Writing chunks_1.jfr ... 219049
Writing chunks_2.jfr ... 237447
Writing chunks_3.jfr ... 218449
$ jfr summary chunks_0.jfr
Version: 2.1
Chunks: 2
...