Optimum OS partition size?

I have a two-years old Dell XPS 8930. It came with a 2TB hard drive. I 1.5TB and 1TB hard drives from its predecessor home build. I'm awaiting delivery of a 1TB WD SN550 NVMe SSD drive, on which I intend to do a clean install of Windows 10. I'll then use the 2TB hard drive for storage. In my current set-up, having relocated various user folders from the C: drive to the other two hard drives, only about 450GB of the 2TB boot drive are in use.

My question, therefore, is what to do about the new 1TB SSD? What are the reasons for and against keeping it as a single "C:" drive vs. partitioning it into more than one logical drive? And if I do partition, what's the optimum size for the C: drive containing Windows 10?

TIA

P.S. If it matters to this question, my current Windows version number is 1903. Having just today created the installation USB flash drive, I expect that it's version 1903 that will be installed on the new SSD.

P.P.S. I understand that doing a clean install will necessitate reinstalling programs. And, I've collected both installation programs and web links, as well as license numbers; I also today downloaded drivers from Dell. If there's a strong reason for cloning the existing hard drive, I'm open to reason.

Each method has a pro / con and you will have preferences.

A backup image can be:
a) in the cloud
b) on an external hard drive
c) on another partition on the same drive

Some place Windows and applications on a SSD and everything else on another drive.

Things to consider:
a) how often are drives tested
b) how often are files backed up or images made
c) whether the computer/drives are needed for work/travel
c) what is the risk of fire, flood, other weather conditions, etc. that could cause loss.
d) loss of internet access
etc.

Hi there
try and use GPT rather than MBR these days if you partition a Disk -- Classical MBR only allows 4 primary partitions, GPT doesn't have any limits.

You can of course use "Logical Drives" for partitioning but I'd really advise against using those --- for dual booting, backing up the OS and all sorts of things using physical partitions is far less likely to cause any sort of aggro.

As for the size of the OS --it's always a good idea (certainly for Windows) to separate the OS and the applications installed on it completely separate from your data so a re-installation / restore of the OS means you don't lose your data.

Size will depend on what you have installed, space needed for other things you want to install etc -- 70 - 80GB should be plenty for the Windows OS (less if you only install a few things). The rest of the HDD you can use for data, backups, other OS's VM's etc etc all in their own physical partitions.

I run W10, Photoshop, Firefox,Office 2019,Skype, SAPGUI (access SAP Database systems) , VMWare WKS , Macrium, VLC and a few other things on 80GB of Windows OS partition .

My version is W10 pro Workstation edition -- still plenty of space left for Windows updates etc etc.

Cheers
jimbo

I have also jumped into the GPT bandwagon even if I was quite reluctant at first. For normal usage (and always moving user data folders to a secondary partition), I use 50-75GB for x86 and 75-150GB for x64 (system partition). I have found out having too big OS partition may lead to humongous $MFT size and slowdowns, specially in traditional HDs.

I always have 30GB+ free on system partition. Your mileage may vary of course. It's also very important to do regular cleanups+Backups.

I assume this new 1 TB SSD is the only SSD you will have.

A Windows installation plus the typical dose of programs isn't likely to take up more than 100 to 300 GB. Are you the exception to this general rule? I've never used even 50 GB.

You say you want to use the older HDDs for storage.

How much personal data do you have, in GB?

What do you intend to do with the 700 plus GB of empty space you will likely have on this new SSD? It certainly shouldn't be left unused and empty.

I would think that the SSD would be a prime location for at least some data (either on C or a separate D), with standard HDDs used as backup--either internally or externally for both your personal data and your Windows installation (via imaging).

I wouldn't think you need to bother with logical drives.

You can certainly re-adjust the size of C after you've been in operation for a while, but you ought to be able to make a highly educated guess based on your current system---after analyzing the growth rate of C in the past. Offhand, Windows tends to grow by less than 5 GB per year via updates in my experience.