RAID 0/1/5/6/10 and ZFS RAID-Z usable capacity, efficiency, fault tolerance, wri...

{ "method": "GET", "queryParams": { "diskTb": 4, "disks": 4, "level": "raid5" }, "type": "http" }

{ "example": { "asOf": "2026-10-11T20:19:40.243Z", "degraded": false, "disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.", "diskTb": 4, "disks": 4, "disksTotalInstalled": 4, "efficiencyPercent": 75, "faultTolerance": 1, "faultToleranceBestCase": 1, "label": "RAID 5 (single parity)", "level": "raid5", "notChecked": [ "filesystem and metadata overhead, ZFS slop space and reserved blocks (real usable space is a few percent lower)", "performance beyond the textbook write penalty: controller, cache and workload dominate", "…2 more" ], "randomWritePenalty": 4, "rawTb": 16, "reasons": [ "With single redundancy, a read error during rebuild may mean data loss for the affected stripe (and an aborted rebuild on some controllers).", "Capacity is in decimal terabytes as sold; operating systems that report TiB show about 9% less.", "…1 more" ], "rebuild": { "probabilityOfReadError": 0.6171071140248879, "terabytesRead": 12, "ureOneErrorPerBits": 100000000000000 }, "source": "computed locally (RAID level definitions)", "spares": 0, "summary": "RAID 5 (single parity), 4 x 4 TB: 12.00 TB usable (10.91 TiB), 75.0% efficient, survives 1 disk failure. Rebuild reads 12 TB: 61.7% chance of an unrecoverable read error.", "usableTb": 12, "usableTiB": 10.9139, "verdict": "REBUILD_RISK_HIGH" }, "type": "json" }