Yes, the individual HDD and related node can fail with 2% probability accordingly to global stat, see Simple adding of more Drives to a node - #9 by SGC
If the node is disqualified on one satellite, it will not receive any payments from it except postponed, if the node is eligible to receive a payout accordingly Minimum Payout Threshold on L1 or if it has zkSync enabled. The held amount on that satellite would be used to recover lost data. The disqualified node will be blacklisted by that satellite, thus Graceful Exit is impossible for that satellite. However, you can call the GE from others if your node is eligible to call it (it should be older than 6 months on the satellite).
Each satellite pays independently, so if your node is not disqualified for the rest, it will continue to receive payments for its services from remained satellites.
If node is disqualified on all satellites, then you cannot use this identity anymore, so if you decided to continue - you will need a new identity, new authorization token and clean healthy storage.
If you have several HDD, you can run several nodes. If they are behind the same /24 subnet of public IPs, they will act as a one big node: the ingress will be shared between them (because we selects only one node from the subnet for the one piece of the one segment of the customers’ data), thus your nodes will act as a RAID on the network level.
If one disk fail - you will lose only that part of your total shared space.
In case of traditional RAID with today’s disks you have a high probability to lost everything during rebuild after the disk failure. See
See also RAID vs No RAID choice for rationales.