What are the possible RAID failure statuses with mdadm on Intel Software RAID?

I have an Intel Xeon-based system running Red Hat Enterprise Linux 9 with an Intel Software RAID configured. I'm using the mdadm utility for managing and monitoring software RAID devices, and I need to understand the possible RAID failure statuses. My goal is to monitor the status of the RAID arrays and be able to identify when they are in a degraded state, missing drives, or have failed devices.

Useful Commands:

1. cat /proc/mdstat
   This command helps identify the active RAID devices. For example, I can see different RAID arrays with various states like "active" and "inactive."

   Example output:

   # cat /proc/mdstat Personalities : [raid1] md125 : inactive nvme2n1[0](S) 1105 blocks super external:imsm md126 : active raid1 nvme0n1[1] nvme1n1[0] 890806272 blocks super external:/md127/0 [2/2] [UU] md127 : inactive nvme1n1[1](S) nvme0n1[0](S) 10402 blocks super external:imsm unused devices: <none> 

2. mdadm --detail /dev/md126
   This command provides detailed RAID volume information. The State field in the output indicates the health of the RAID volume.

   Example output:

   # mdadm --detail /dev/md126 /dev/md126: Raid Level : raid1 Array Size : 890806272 (849.54 GiB 912.19 GB) State : active Active Devices : 2 Failed Devices : 0 Consistency Policy : resync 

RAID Failure and Degradation Scenarios:

• If a Hard Disk is Missing:
  What will be the output and RAID status in the mdadm --detail and cat /proc/mdstat commands? Specifically, how will the RAID array reflect the missing disk's status?

• If a Hard Disk is Offline:
  How will this affect the RAID status shown by these commands? Will the status change to something like offlinesyncing or degraded?

• If a RAID Array is Degraded:
  What status will be reflected in the output? Specifically, how does the term "degraded" appear in the RAID status in both mdadm output and /proc/mdstat?

• If a RAID is in a FailSpare State:
  What is the output in mdadm --detail for a RAID array in this state? How is this state reflected in the status of the RAID array and individual drives?

I have found the following statuses in the mdadm manual:

• Critical Severity:

  • Fail, FailSpare, DeviceDisappeared, DegradedArray

• Warning Severity:

  • RebuildStarted, RebuildNN, RebuildFinished, SparesMissing

Could you explain what these status values mean, especially when monitoring RAID arrays for failure or degradation?

Additional Queries:

1. Is it better to use the mdadm --detail /dev/md<number> command to check the complete RAID status, or should I use mdadm --examine /dev/<disk> on any RAID member disk? For example:

   # mdadm --examine /dev/nvme1n1 

   The output from this command provides information about the disk and its current state, but I am unsure about the relevance of this command compared to mdadm --detail.

Thank you for your assistance.