Hello None of that matters. All of the issues you are concerned about have no bearing on your configuration.     When you use a hardware RAID controller the operating system has no control over the blocks. Any blocks the operating system thinks it is controlling are virtual, so any TRIM/UMAP the OS is doing is against virtual blocks.   Over provisioning happens at a drive level. The SSD manufacturers allocate space for this. If you want to do additional provisioning then some drive manufacturers provide utilities to allow you to manipulate the provisioning, or you can just have unallocated space on the drive. Any unallocated space will automatically be used by the drive, but I don't see a need for this since SSDs are already over provisioned by the manufacturers. Thanks  
Hi, I have: I would like to configure the server with a RAID 5 array for the SSDs and another RAID 5 array for the HDDs.   Regarding the SSDs, I read that: Is (3) above really necessary when it comes to RAID with SSDs?  If so, how do I achieve this?  Do I: only allocate 95% of the available SSD space when creating the RAID volume? OR allocate 100% of the available disk space to the RAID volume and then when I create partitions during OS installation, leave 5% unallocated?
RAID and TRIM Config for R720xd and SSDs