Magician is unable to find a Samsung SSD connected, and cloning to my SDD failed

need more information to help;

What motherboard make and model do you have ?
Where are you connecting your SSD (SATA or M.2)?
Where is your HDD connected to ?(SATA slot_0/1/2/3??)

We've run into a few situations with the SDM program where that disk-cloning program will not detect a Samsung intended destination drive if the SATA controller mode in the BIOS has not been set to AHCI. So check that setting in the BIOS to confirm it's set to AHCI.

Ordinarily setting the SATA controller to RAID is compatible with the AHCI setting in terms of the SATA controller mode compatibility for the Samsung SDM program. So I really don't know what's amiss here. I trust you'll keep us informed.

1. (Just a passing thought, but) it's no secret that early Samsung SSDs had compatibility problems with AMD-based systems but that should have no bearing re your current Samsung 850 EVO.

2. Anyway, while you're "waiting", you might use Samsung's Magician program to check out the health of the EVO. Probably no problem with the drive itself but check it out anyway.

3. And I don't suppose you have a USB external enclosure (or one of those SATA-to-USB adapter cables) for an external connection to the SSD and attempt another disk-cloning operation?

The other obvious alternative at this point-in-time is to simply try another disk-cloning program. Have you considered that?

1. There has been a glitch in the Samsung Magician program that falsely reports the SATA controller has not been set to the AHCI mode even though the RAID setting (which you have set) supports AHCI by default. Unfortunately the SM program reports this as a kind of error.

2. I have no idea what the "partioner" program? is. It's a disk-cloning program that you have previously used? Or is it some kind of SSD/HDD diagnostic program? Try using the HD Sentinel program for testing purposes; it's the one we've been using for years and we've found it totally reliable. See...
https://www.hdsentinel.com/download.php

That's good news.

BTW, we are assuming that the disk-space capacity of the SSD (which will be the recipient of the clone) is sufficient to contain the TOTAL data contents of the HDD source drive. That's right, isn't it? Because if it isn't, you can't utilize this disk-cloning operation.

Try this disk-cloning program which you can download from https://www.fssdev.com/products/casper/trial/

We've been using this Casper d-c program for many years and find it easy-to-use and quite effective. While the program is a commercial one costing $49.99 a 30-day Trial Version is available that you can use.

1. After installing the program and before undertaking the disk-cloning operation close all open programs. (Generally you need not disable your anti-virus program). Ensure your destination drive - the proposed recipient of the clone, your SSD - is properly connected in the system.

2. The opening screen of the program will highlight "Create a Bootable Backup". Click on "Add drive" and a listing of the appropriate destination drive(s) will appear, e.g., your 250 GB SSD.

3. Click on the destination drive's listing and then the "Back up now" button.

4. Casper will run in the background and alert you when the disk-cloning operation is completed. (You can view the actual progress chart by clicking on the Casper icon in the Notification Area on the Taskbar.)

5. Following the (hopefully!) successful disk-cloning operation disconnect (when practicable) the source HDD from the system and boot SOLELY to the connected destination drive, your SSD. As a general proposition it's a good idea (whenever practicable) for the newly-cloned drive to be connected to the motherboard's first SATA data port/connector, usually designated SATA 0 or SATA 1.
Also, check the system's BIOS/UEFI to ensure the cloned drive is now first in boot priority order.

6. Work with the newly-cloned SSD for a while to determine it boots & properly functions before reinstalling the HDD which will now serve as a secondary drive in your system.

7. Ordinarily Casper will utilize the entire disk-space of the destination drive to contain the data contents from the source drive. In some cases the program will create a partition on the destination drive (your SSD) only to the extent of the total data cloned. If that does happen, you can use Disk Management to extend the partition to encompass the total disk-space available on the SSD; it's a simple operation.

I didn't see your last response before I responded above.

The Macrium Reflect program is fine; used by many PC users. Apparently the volume of data you plan to clone is greater than the disk-space capacity of your SSD. You haven't provided any details as to the amount of data involved but that seems to be the case.

If you want to continue pursuing a disk-cloning operation you will have to reduce the volume of data on your source disk - the HDD, so that it will 'fit' on the SSD destination drive.

Hallelujah!