Question Partitioning drive during Windows 10 install

[JBHapgood]

I will be doing a clean install of Windows 10 for a new computer, on a virgin 1TB SSD. I want to partition the SSD into a 750GB system (C: ) partition and 250GB data (D: ) partition. What should I do during Windows installation to set that up? Can the installer create and format both partitions, let me leave the space for the data partition unallocated, or something else? (This will be the first time I've installed Windows 10. I'm replacing a 9-year-old computer that runs Windows 7.)

FYI, I want the separate partitions to facilitate backup. The D: partition on the SSD will contain files to which I want fast access. All other data will go on a hard drive. The files on D: and the hard drive are backed up frequently, directly to an external drive. The system partition (C: ) is backed up less frequently using a drive imaging program.

 

[USAFRet]

Yes, you can size those partitions during the install.
And remember...you don't have "1TB" to work with, but rather 931GB. Adjust accordingly.

 

[JBHapgood]

Update to help others who might want to partition a drive during Windows 10 installation

On my first installation attempt, I used the installer to create and format two partitions, one with 75% of the drive and the other with 25%. Once Windows was installed, I saw that the installer in its infinite wisdom had made the small partition the C: drive and put Windows there.

So I rebooted and reinstalled Windows. I had the installer wipe the drive, and then made one partition that took up 75% of the drive space. I left the rest unallocated. The installer then put Windows on that partition.

I used the drive partition tool to format the unallocated space, which it insisted on calling F:. That was because Windows had assigned D: and E: to the two optical drives. Manually changing the drive letters on those drives and the new partition finally got me the configuration I wanted.

 

[USAFRet]

A Windows install will install on whichever partition YOU designate.

 

[JBHapgood]

A Windows install will install on whichever partition YOU designate.

I'll believe you, but I couldn't see any obvious way to designate a partition. The issue of multiple partitions is poorly documented, which is why I originally posted this question. If you could describe how to designate a partition, that would surely be more helpful to future searchers than my solution.