Partition Ubuntu

Partitioning is mostly only useful if you will have a large number of small files which could cause the inode table to be full before the disk/partition runs out of space. Otherwise, you might run into the problem at some point that you have lots of space on one partition, while another is full ... from your mention of Mac and dual boot, I assume a typical desktop use. With 250G, most likely you shouldn't really need multiple partitions. Also, the separate boot partition nowadays isn't really necessary anymore; in earlier times, the boot loader could run into problems when the kernel image was located at some higher blocks out of the reach of some BIOS routines. Modern loaders like GRUB will not have any problems with that. Apart from that, you will of course need a swap partition (or should have one anyway), though its size would depend on the memory of the machine and your planed usage. The old "twice the main memory" rule does not necessarily apply anymore, at least for typical use and abundant main memory, so e.g. if you have 8G of mem, you could get bye with 4-8G of swap space ... and may never touch it while running the system ... ;)

Because it only choose whole HD for Linux or use advanced mode and then choose free 250G space to partition Linux Ubuntu, so I cannot choose whole HD as 250 GB  used for Mac

Thanks, let me try it and feed back here