Thank you for contacting the Intel community.
First of all, I strongly recommend backing up all your information to avoid any lose of data.
Usually, on most systems you will get the Crtl-I option if your system is set to RAID mode in the BIOS and when the system boots you can press Crtl-I on your keyboard to access the Ctrl-I BIOS and reset the RAID to non-raid disks, since it is a RAID 1 you will not lose any data, I understand that you don’t get this option so you should be able to do it from the Intel® Rapid Storage Technology application, you will need to high light the RAID volume and it will give you an option to reset the RAID to non-raid disks.
If you don’t get this option at all, would you please post a picture of the IRST so I can take a look at it?
As mentioned, we do not get the option for Ctl-I during boot even when Raid is enabled in Bios. This might be because of the new Dell Bios for XPS 8920. Also the application does not have any options to even delete the Raid.
To resolve the slowness due to one drive being SSD and the other traditional ATA, re removed the traditional drive from the system - breaking the Raid1. Now PC is working fast - we are getting notification that we have a broken Raid. but that is OK since we did not want to have a Raid in the first place. If we reformat the traditional ATA drive in another system and put it back to this PC, will Rapid Storage identify it as part of the previous Raid1 or a new NON-Raid drive? How does the Rapid Storage taggs Hard drive as part of Raid. We did not see the physical drive in the Win 10 Disk Management at present
I am really upset with Dell not providing support for Bios and system settings for Rapid Storage chipset, unless we buy the second drive from them.
Thanks for your help and advice,
If you format the HDD in another system is fine, but you will need to get the Ctrl – I option to set it as non-raid disk and after that the system will see the drive as any normal drive, you can also use a third party software to reformat the HDD.
The IRST will see the drive as normal drive if it is not part of a RAID anymore; if it is part of a RAID it will show two drives in a RAID volume. You can see the picture attached.
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You can delete the array from in Windows via the IRST app in RAID mode but what Ivan failed to tell you is that you need to boot into windows in RAID mode first because the IRST app cannot see your Raid array in AHCI mode, the link below explains how to change from AHCI to RAID or RAID to AHCI.
Once you have made the change you can boot into windows in either modes.
It's a shame that in 2017 Intel and or Microsoft still have not made a driver that installs both AHCI and RAID drivers in the one driver install.