Hello,
sorry, I don't know in what subdepartment of this forum this question belongs:
I already made a raid 10 confuguration with rst, which works after initialisation.
It is a raid 10 with 4 harddisks. Also I have two other drives not in an raidarea.
The largest single drive is for data only. The second single drive is free for now.
Raid 10 consists of 4 drives of 3TB each. The large single is 4TB, the other 2TB.

When I in RST click on the smallest 2TB free drive I can see left in the RST util
that this drive is to be set marked as a spare drive. (in dutch: reserve disk).
From the help function of rst I understand that it is for data-safety if a drive fails.
I thought raid 10 (mirrored-stripe) was save enough of its own nature, why a spare?

OK, I will use the drive for this purpose, but what are the requirements for this disk?
Is the size of any importance? Is the 2TB enough for this raid 10 of 4x3TB? And what
if I don't use the spare disk as "reserve"? Will my raid system be in more danger?

It is now the 3rd time I create the raid 10, and two times earlier the raid became
corrupted, and files could not be restored, after countinuous chckdsk startup errors.
Gladly I got backups of my data on a different system, so, after days copiïng, i could
use the system again. I am thinking leaving the raid system, when this happens again.
Maybe, with the spare reserve disk, it wil be possible to restore if raid fails once more.

Must say, the OS itself works perfectly on a PCIe RamDisk, apart of the mb controllers.

Henri