Resource Cheatsheet
A+ Core 1 3.2: Storage Cables
Professor Messer A+ 220-1201 objective 3.2 — SATA revisions and speeds, the one-to-one power and data connectors, no daisy chaining, and eSATA.
- Updated
- Reading time
- 4 min read
- Detail
- A+ Core 1
- Detail
- Storage Cables
On this page
In one line: SATA is a simple one-to-one interface — one 15-pin power cable and one 7-pin data cable per drive, no daisy chaining, so port count is drive count — with eSATA as its externally-connectored twin.
Companion to: Professor Messer, CompTIA A+ 220-1201 Core 1, objective 3.2 (Storage Cables). The full version is the Storage Cables class notes; the section overview is the Section 3 sheet.
SATA speeds
| Revision | Max speed |
|---|---|
| SATA 1.0 | 1.5 Gbps |
| SATA 2.0 | 3 Gbps |
| SATA 3.0 | 6 Gbps — the number to know |
| SATA 3.2 | 16 Gbps (via SATA Express, over PCIe lanes) |
1.0 → 2.0 → 3.0 each doubles the last. 3.2’s 16 Gbps breaks that pattern — it’s PCI Express, not faster native SATA signalling, and applies to SATA Express devices specifically, not ordinary SATA drives.
The two connectors
| Connector | Pins | Carries | Shape |
|---|---|---|---|
| Power | 15 | Power | Longer |
| Data | 7 | Data | Shorter |
- Some drives also accept the older Molex power connector as a fallback.
- Both connectors are keyed — only fit one way round.
One-to-one, no daisy chaining
- One cable, one port, one drive. Always.
- No daisy chaining — SATA cannot share a cable across multiple drives.
- Port count = maximum drive count. Six SATA ports on a motherboard support at most six drives, full stop.
- Mixed SATA 2 / SATA 3 ports on one board are common — put fast SSDs on the SATA 3 ports, since a fast drive on a slow port is capped at the port’s speed.
eSATA
| Point | Detail |
|---|---|
| What | The external version of SATA |
| Signal | Effectively the same as internal SATA |
| Connector | Different shape from internal SATA — not interchangeable |
| Cable length | Approximately 2 m |
| Internal SATA shape | Distinctive L shape |
| Unfamiliar rear-panel connectors | Worth checking whether they’re eSATA |
Beyond the exam: eSATAp (Power over eSATA) combines eSATA with USB power in one port, serving either device type and powering a bus-powered external drive.
Troubleshooting
| Symptom | Check first |
|---|---|
| Drive shows one boot, vanishes the next | Data cable seating — reseat or swap before suspecting the drive |
| External “SATA-style” connector won’t fit any port | Probably eSATA, not USB — confirm the shape, check for an eSATA port or expansion card |
| Fast SSD underperforming | Confirm it’s on a SATA 3 port, not SATA 2 |
| Connector resists insertion | Wrong port or orientation — SATA/eSATA connectors are keyed; never force it |
🔐 Security notes
- Physical SATA access = raw disk access, bypassing every OS-level control. Full-disk encryption is the control that survives an opened case; a locked user account is not.
- eSATA is a fast, low-friction exfiltration path — often overlooked by device-control policy that only covers USB. Disable unused eSATA ports and name them explicitly in DLP rules.
- A swapped or added drive is easy to miss on a simple bus. Case-intrusion detection and drive-serial asset tracking are the relevant controls.
- One-to-one cabling actually helps here: an unexpected extra drive or unfamiliar cable run is more conspicuous during inspection than on a shared bus.
- Decommissioned drives stay readable over SATA via a cheap USB-to-SATA adapter — certified wipe or physical destruction before disposal, never just “pull and set aside.”
Practice drills
1. SATA 1.0, 2.0, 3.0 maximum speeds?
1.5 Gbps, 3 Gbps, 6 Gbps — each one double the last.
2. Why does SATA 3.2's 16 Gbps break that doubling pattern?
It’s reached via SATA Express, running over PCI Express lanes — not further native SATA signalling — and applies to SATA Express devices, not ordinary SATA drives.
3. Pin counts for SATA power and data connectors?
Power: 15 pins (the longer connector). Data: 7 pins (the shorter one).
4. Can two drives share one SATA data cable?
No. SATA is strictly one-to-one — no daisy chaining.
5. A motherboard has six SATA ports. Maximum drives?
Six. Port count is the hard ceiling.
6. How does eSATA's connector compare to internal SATA's?
Different shape entirely — not interchangeable, even though the signal on the wire is effectively the same.
7. A drive appears in BIOS one boot, not the next. First check?
Reseat or swap the data cable before suspecting the drive itself.
8. eSATA's approximate cable length?
About 2 metres.
Key takeaways
- SATA 1.0/2.0/3.0 double each time: 1.5 → 3 → 6 Gbps. 3.2’s 16 Gbps is SATA Express over PCIe, a different mechanism.
- 15-pin power, 7-pin data, both keyed — and strictly one-to-one with no daisy chaining.
- Port count is drive count, full stop; mix SATA 2/3 ports deliberately, fast drives on SATA 3.
- eSATA = same signal, different connector, ~2 m cable — not interchangeable with internal SATA.
- A loose data cable, not the drive, is the first suspect for an intermittently missing drive.