Ordinary SATA motherboard cannot recognize SAS hard drive through a passive adapter cable.
The connectors and high-speed differential pairs look similar, but that does not mean both ends run the same protocol. An adapter that truly allows a SATA host to access a SAS drive must contain an active protocol bridge that understands both SATA and SAS.
INIC6711 is a chip worthy of attention in this type of product.
Existing teardown evidence shows that it can sit between a SATA host and a SAS drive:
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From the motherboard side, it should behave like a SATA device; from the hard disk side, it should assume the role of SAS initiator and convert ATA requests into SAS/SSP/SCSI requests.
This is not changing pins or simply adjusting levels, but a semantic conversion of commands, status and errors between two sets of storage protocols.
Clarifying the Direction of โSAS-to-SATAโ
“SAS-to-SATA bridge” may refer to two opposite connection directions in industry materials.
Direction Covered in This Article
The goal of this article is:
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This arrangement allows an ordinary computer with only a SATA AHCI controller to access a SAS HDD or SAS SSD.
The “convert to SATA” here means that the host side presents it as SATA, rather than actually transforming the inside of the SAS hard disk into a SATA disk.
The Opposite Direction Used in Enterprise Storage
Marvell and other manufacturers also call some products SAS-to-SATA protocol converter, but the usage is usually:
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These bridges present SATA drives to dual-port SAS storage systems and focus on enterprise features such as high availability, dual-port operation, and T10-DIF.
It and the INIC6711 solution have different connection directions and cannot be replaced by just the words “SAS/SATA Bridge”.
Why a Passive SFF-8482-to-SATA Cable Does Not Work
Both SATA and SAS use high-speed serial differential pairs, and 3Gb/s and 6Gb/s rates have appeared in common generations.
But the same physical rate does not equal the same protocol stack.
| level | SATA | SAS |
|---|---|---|
| Upper level command | ATA Command | SCSI Command |
| transmission protocol | SATA FIS | SSP, SMP, STP |
| Typical host | AHCI/SATA Controller | SAS HBA/RAID Controller |
| port | single port | SAS disk common dual port |
| topology | Point-to-point, Port Multiplier | Point-to-point, Expander, multipath |
| Management capability | ATA/SMART | SCSI Inquiry, Sense, Log Page, etc. |
A stock SATA controller will not issue SAS SSP commands and will not complete the SAS device discovery and login process.
So this connection has no protocol conversion capability:
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Common results are:
- The hard disk cannot be seen in the BIOS;
- There is no new device for the operating system;
- The hard drive may power on and spin up, but the data link cannot be established;
- Incorrect and repeated hot plugging may also damage the connector or data.
Passive SFF-8482 transitions are typically only available on one side that is already protocol-provided by a SAS HBA, or are used to repin compatible signals and power supplies.
To allow the SATA Host to access the real SAS Drive, an active bridge must be added.
Where INIC6711 Sits in the Protocol Stack
From the functional level, INIC6711 can be drawn as two ports and a conversion core:
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The external SATA host does not see the SAS topology directly, but rather sees the SATA devices presented by the bridge.
The bridge must handle much more than LBA reads and writes, including:
- device identification information;
- capacity and logical sector size;
- read and write cache status;
- Flush, TRIM/UNMAP and other command differences;
- error code and SCSI Sense to ATA Error mapping;
- SMART or forwarding of health information;
- sleep, standby and reset;
- Timeout and link retry.
Whether these conversions are complete determines whether it is “readable” or can be used reliably for a long time.
What the Existing Hardware Evidence Confirms
The currently public INIC6711 complete datasheet, reference schematic diagram and firmware programming guide are difficult to find.
Therefore, the information must be divided into three layers: “confirmed by clear disassembly”, “common characteristics of multiple boards” and “still needs actual measurement”.
Maiwo K308SAS: A Clearly Documented Dual-Bridge Design
K308SAS is a SAS USB Dock. The public teardown clearly records:
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Each of the two bridge chips has its own:
- 25 MHz crystal oscillator;
- XTX
XT25F04BSPI Flash; - independent bridge function.
XT25F04B is 4 Mbit, which is 512 KB of SPI NOR Flash.
This structure shows that INIC6711 is responsible for the conversion of SAS Drive to SATA; INIC3639 is responsible for the conversion of SATA to USB.
If the target is just to connect to a SATA host, INIC3639 is not required.
Blueendless BS-HD01S: A Readable Main-Chip Marking
You can read directly in the disassembly of another SAS USB Dock:
INIC6711EN-CS, QFN-64;INIC3639PN-FL, QFN-48;- Two 4 Mbit SPI Flash;
- Two 25 MHz crystal oscillators;
- multi-channel DC-DC power supply.
This set of evidence supports the following judgment:
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ADPTSAS-L01 VER006: A Single-Drive Active Adapter
ADPTSAS-L01 VER006 is a single-disk product closer to pure SAS DriveโSATA Host.
Its function path is:
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Published testing shows that an ordinary SATA controller can identify, read, and write several tested SAS drives through this board.
However, the silk screen of the main chip of this board has been worn away. Based on the QFN-64 package, peripheral structure and similar products, it is highly suspected of INIC6711, but photos alone cannot be written as 100% confirmation.
This qualification must be retained.
Functional Hardware Layout of a Single-Drive Board
Based on the existing disassembly, the INIC6711 single-disk bridge board can be drawn as a functional block diagram first:
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This picture can only describe the module relationship and cannot replace the pin-to-pin schematic diagram.
The key information currently missing still includes:
- QFN-64 complete pinout;
- The voltage and power-on sequence of each power rail;
- SATA/SAS PHY pin number;
- crystal oscillator load capacitance requirements;
- SPI boot mode;
- GPIO, LED and debugging pins;
- firmware version and configuration area format.
Why SFF-8482 Port A Alone Is Sufficient
A dual-port SAS drive normally has a Primary Port and a Secondary Port.
A single-host bridge needs only one of those ports.
Teardown evidence shows that K308SAS leaves SFF-8482 pins S8โS14 for the second port unconnected and uses only the Primary Port signal segment S1โS7.
The common SFF-8482 signal assignment can be summarized as follows:
| signal segment | Purpose |
|---|---|
| S1 | GND |
| S2/S3 | Port A A set of differential signals |
| S4 | GND |
| S5/S6 | Port A Another set of differential signals |
| S7 | GND |
| S8๏ฝS14 | Port B, can not be connected to |
Different data will label the differential pair IN or OUT according to the viewing direction of the host/device. When drawing the schematic diagram, the direction cannot be judged by the text name alone.
Use a multimeter in continuity mode to confirm the connections on the physical board, then determine TX/RX from the chip-side coupling capacitors and trace direction.
Using only Port A removes SAS dual-port and multipath capabilities, but that is not a functional loss for a single SATA host.
The SATA 22-Pin Side Carries Both Data and Power
ADPTSAS-L01 type 1 board uses SATA 22Pin input, usually includes:
- SATA data 7Pin;
- SATA power supply 15Pin;
- 5V, 12V and ground;
- bridge.
SAS hard drive body are likely to be directly sent to the SFF-8482 after being protected and filtered from SATA Power.
The bridge chip requires DC-DC converters or LDOs to generate its internal rails.
In the ADPTSAS-L01 photo you can see two switching power supply areas with inductors:
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However, which combination of 3.3V, 1.8V, and 1.2V VIO and VCORE are cannot currently be determined based on photos alone.
Measure the following on a known-working board:
- Voltage between both ends of the inductor and ground;
- timing after power on;
- Current when no load and hard disk is started;
- Whether the crystal oscillator is starting to oscillate;
- Flash supply voltage;
- reset pin release time.
Power Delivery Is Easy to Underestimate
3.5-inch enterprise SAS HDD may draw significantly higher startup current than a regular 2.5-inch SATA SSD.
Protocol compatibility does not mean the board will run reliably from an undersized power adapter.
Insufficient power supply may appear as:
- The hard drive spins up repeatedly;
- SATA link training failed;
- BIOS can be seen occasionally, sometimes not;
- Disk drops during heavy load;
- SMART reports interface CRC or abnormal power outage;
- bridge resets the moment the hard disk starts up.
When designing the power supply, you should read the 5V and 12V currents on the nameplate of the target hard disk and leave margin for the startup peak value.
Do not connect multiple enterprise disks in series from the motherboard SATA power cable.
For initial testing, use a reliable independent supply with a clearly specified current rating and ensure that the bridge board and host share ground.
The 4 Mbit SPI Flash May Be the Largest Development Barrier
Multiple teardowns show a dedicated 4 Mbit SPI NOR beside INIC6711. It is not an optional detail.
Flash may save:
- main control working firmware;
- SATA Device Identify template;
- SAS PHY initialization parameters;
- ;
- LED, GPIO and power strategies;
- manufacturer, product string;
- firmware version and verification information.
There is currently no evidence that the bare INIC6711 already contains complete firmware that can work independently.
Therefore the following combination does not guarantee startup:
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A more reliable research sequence is:
- records the model and behavior when the original board is working normally;
- reads the entire contents of SPI Flash;
- Read the same content at least twice and compare the checksums;
- Save the original dump and do not modify it directly on the original file;
- Prepare a spare Flash of the same model;
- Verify copied Flash under recoverable conditions;
- finally analyzes the configuration area and firmware area.
When reading the firmware of your own device for maintenance and compatibility research, you should also pay attention to local laws, licensing and manufacturer intellectual property restrictions, and should not distribute firmware images to the public at will.
How to safely read the on-board SPI Flash
First confirm the Flash screen printing, capacity and power supply voltage.
XT25F04B states that it is a 4 Mbit, 512 KB, 3V SPI NOR.
Do not clamp the programmer directly without confirming the voltage.
Recommended process:
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First read three times:
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Only three identical checksums provide initial confidence that the clip contact and read voltage are reliable.
If the checksum changes repeatedly, subsequent operations should be stopped and troubleshooting:
- SOIC clip poor contact;
- Other chips on the board interfere with the SPI bus;
- The programmer has insufficient power supply capability;
- Flash needs to be desoldered and read offline;
- Model or capacity identification error.
Donโt click โEraseโ first and then look for a backup.
Reconstructing the Minimum System from the PCB
Drawing the entire schematic diagram based solely on photos can easily lead to inferences being taken as facts.
The network list should be established step by step by module.
Step 1: Confirm connector and ground
Mark first:
- SATA Data 7Pin;
- SATA Power 15Pin;
- SFF-8482 S1๏ฝS14;
- SFF-8482 power segment;
- Large area ground plane;
- Is the mounting hole grounded?
Step 2: Trace four pairs of high-speed differential lines
Need to confirm:
- SATA Host TXยฑ;
- SATA Host RXยฑ;
- SAS Port A TXยฑ;
- SAS Port A RXยฑ.
Record whether each differential pair passes through:
- AC coupling capacitor;
- common mode inductor;
- ESD protection;
- 0ฮฉ resistor;
- test point;
- via layer change.
SAS/SATA differential impedance is usually designed at 100ฮฉ, but the specific stackup, line width, spacing and reference plane must be calculated from the actual parameters of the PCB factory.
Do not estimate line width directly from photos.
Step 3: Measure the power tree
Create a table for each inductor and LDO output:
| serial number | input voltage | output voltage | Power-on time | Connect load |
|---|---|---|---|---|
| U2/L1 | to be tested | to be tested | to be tested | INIC6711 A certain power domain |
| U4/L2 | to be tested | to be tested | to be tested | INIC6711 A certain power domain |
| Flash VCC | to be tested | to be tested | to be tested | SPI NOR |
“To be tested” is more reliable than guessing a voltage based on the package.
Step 4: Confirm crystal oscillator and Flash
Use an oscilloscope to confirm the 25 MHz crystal oscillator start-up time and steady-state waveform.
Trace SPI signals CS#, SCLK, MOSI, and MISO, and observe whether the controller reads the Flash immediately after power-on.
A logic analyzer can reveal:
- Whether to start reading from address 0;
- How many bytes were read;
- Whether there is duplicate verification;
- Whether to re-read the configuration after link training fails;
- Whether the master writes back the status to Flash.
Step 5: Handle LEDs and Unknown GPIO Last
LED, buttons, hard disk presence detection and fault indication are low-speed parts.
First let the bridge recognize the hard drive stably, and then complete these signals, the troubleshooting scope will be much smaller.
INIC6711 Does Not Preserve Every SAS Feature
Presenting a SAS drive as a SATA device inevitably removes capabilities that exist only in SAS/SCSI.
Generally cannot be expected to retain:
- dual port active/active;
- multipath I/O;
- SAS Expander topology;
- SES chassis management;
- Complete SCSI Mode Page;
- Complete SCSI Log Page;
- protection information/T10-DIF;
- Error recovery strategies for enterprise RAID controllers;
- Same queue depth as SAS HBA;
- All manufacturer diagnostic commands.
SMART is completely transparent and whether the temperature and error logs are readable also depends on the firmware implementation.
Therefore, it is suitable for solving “how an ordinary SATA host accesses a SAS disk”, which does not mean providing a complete SAS infrastructure.
520/528-Byte Sectors Are a Common Compatibility Trap
A large number of used enterprise SAS disks from storage arrays, may use:
- 512-byte logical sector;
- 4Kn;
- 520 bytes;
- 528 bytes;
- format with protection information.
Common SATA/AHCI environments typically operate on 512, 512e, or 4096 byte sectors.
Even if INIC6711 can establish a SAS link, it does not mean that it can losslessly convert the 520/528 byte format into a format acceptable to the SATA host.
Possible symptoms include:
- can identify the model but the capacity is 0;
- BIOS stuck in hard disk detection;
- Operating system reports I/O Error;
- Reading capacity abnormality;
- can only read and cannot create partitions;
- Some disks are normal, but some disks with the same interface fail.
If the hard disk is in 520/528 byte format, it should usually be connected to a real SAS HBA first, and then reformatted to the target sector size after confirming that the data does not need to be retained.
Reformatting clears data and may take a long time. Disks containing important data cannot be used directly for testing.
Drive Firmware, Link Speed, and Capacity Can Also Limit Compatibility
INIC6711 is often used in 6Gb/s SAS/SATA scenarios, but public information is insufficient to establish a complete compatibility matrix.
Verify each of the following separately:
- Whether SAS-1, SAS-2, and SAS-3 hard drives can all be connected at reduced speed;
- Whether 512n, 512e, and 4Kn are all reported correctly;
- Is the capacity above 2TB complete?
- HDD and SAS SSD are supported;
- Whether the Inquiry and Mode Page of firmware from different manufacturers are compatible;
- Whether the write cache and forced unit access are correctly mapped;
- Whether secure erase, Sanitize, TRIM/UNMAP is supported;
- Whether standby, hibernation and hot swap are stable.
“One disk is successful” cannot be used to deduce “all SAS disks are compatible”.
Estimating the Performance Ceiling
If both the SATA side and the SAS side run 6Gb/s, the raw rate of the link is the same, but the effective throughput is still affected by protocol overhead and bridge implementation.
SATA 6Gb/s is usually lower than the original 750MB/s, and the actual upper limit of high-performance SSD is about 500~560MB/s.
With mechanical SAS HDDs, the platter itself usually becomes the bottleneck first, and the bridging overhead is not necessarily noticeable.
For SAS SSD, it is important to observe:
- sequential read and write throughput;
- 4K random IOPS;
- queue depth reduction;
- Flush delay;
- long-term writing stability;
- temperature and disc drop;
- error recovery time.
Because the bridge maps SAS/SCSI behavior into SATA/AHCI semantics, an enterprise SAS SSD may lose some of its queueing and error-recovery advantages.
Verifying the Bridged Drive in Linux
Perform read-only recognition first, do not partition or format immediately.
View the kernel log:
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Check after connection:
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Read information from the target device:
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If smartctl automatic detection fails, you can try SAT device type according to the output:
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Not all INIC6711 firmware guarantees full SMART passthrough; failure does not necessarily indicate a bad hard drive.
/dev/sdX must be replaced with the actual test disk. Before executing any write command, confirm the device identity with at least three items: model, serial number, and capacity.
The first round of performance testing should remain read-only
First confirm that the kernel does not continuously report errors:
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Run a 60-second sequential read-only test:
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Also watch:
- Whether ATA link reset occurs;
- Whether I/O timeout occurs;
- Whether the hard disk is re-enumerated after being offline;
- bridge chip temperature;
- 12V voltage drops during startup and load;
- SMART interface error count is increased.
After read-only operation is stable, use a disk with no important data for write and power-loss recovery tests.
What to Check in Windows
In Windows check at least:
- Controller and disk model in Device Manager;
- Capacity and sector status in disk management;
- Whether CrystalDiskInfo can read health information;
Disk,storahci,stornvme,Ntfserrors in event viewer;- Recognition consistency after cold start, restart, and sleep recovery;
- Whether a device reset occurs during a large file transfer.
If the bridge appears as a normal SATA Device, Windows will typically still access it by the AHCI path without displaying the full SAS topology.
Donโt think that cache refresh, error handling and power-down behavior have been verified just because the hard drive model is displayed in the device manager.
Hot-Plug Safety Requires More Than a Removable Connector
Both SATA and SAS support corresponding hot-plug mechanisms, but the bridge board also introduces additional state machines.
All of the following conditions must be met:
- Host SATA port enables Hot Plug;
- power connector has correct precharge and contact sequence;
- INIC6711 firmware can handle hard drive removal and re-login;
- The operating system uninstalls the file system first;
- bridge will not reset due to power glitches;
- hard drive motor after it has completely stopped.
A bare board without a casing, backplane and suitable connectors should not be plugged or unplugged repeatedly while powered on.
Identifying an Active Bridge Versus a Passive Adapter
When purchasing a so-called “SAS to SATA” product, you can check:
| Checkpoint | active bridge board | Passive adapter board |
|---|---|---|
| main control chip | has QFN/BGA master control | Usually not available |
| crystal oscillator | Common 25 MHz crystal oscillator | Usually not available |
| SPI Flash | Common 8Pin NOR | No |
| DC-DC/LDO | has multiple low-voltage power supplies | Rarely needed |
| PCB complexity | Multi-layer, high-speed differential and power area | mainly connector wiring |
| Common SATA host identifies SAS disk | may support | does not support |
“SFF-8482 to SATA 22Pin” is only a connector description and cannot prove the existence of a protocol bridge.
If the product photo only shows connectors at both ends and straight-through cables, it should be assumed that it does not have SASโSATA protocol conversion capabilities, unless the manufacturer clearly provides the main control model and actual measured compatibility instructions.
Suitable and unsuitable scenarios for the INIC6711 solution
Suitable Uses
- Temporarily reads known compatible SAS drives;
- Single-disk data migration on ordinary SATA host;
- uses a 512/4Kn format SAS HDD at low cost;
- Repair or research existing active bridge boards;
- Single-disk scenario that does not require multipathing, expander, and enterprise management functions.
Unsuitable Uses
- saves the only important data;
- requires dual-port high availability;
- requires SAS Expander or JBOD management;
- relies on T10-DIF/protection information;
- requires full SCSI logs and diagnostic commands;
- Multi-disk concurrency and high queue depth services;
- 520/528 byte disk is not reformatted;
- is an unattended production storage that lacks disk drop monitoring.
If the value of the data is higher than the value of the hard disk, give priority to using LSI/Broadcom SAS HBA with complete data and make a copy of the data first.
Minimum Validation Checklist Before Reproducing the Board
If the goal is to redesign the PCB based on an existing single-disk board, at least the following evidence should be obtained first:
- master control silk screen can be confirmed to be
INIC6711orINIC6711EN-CS; - SPI Flash model, capacity and voltage have been confirmed;
- Flash has completed multiple consistent reads;
- 25 MHz crystal oscillator has been confirmed with an oscilloscope;
- Each power supply voltage and power-on sequence have been recorded;
- Four pairs of SATA and SAS high-speed lines have completed on-off mapping;
- AC coupling, resistor and ESD component locations documented;
- SFF-8482 Port A and Port B usage status confirmed;
- At least three SAS disks from different manufacturers have been identified;
- 512n, 4Kn and large-capacity disks were tested separately;
- Repeat cold start and restart at least 20 times each;
- Long-term read-only, write, flush and power-off recovery completed;
- SMART, temperature and error log transparent transmission capabilities have been recorded;
- firmware recovery method has been verified.
If any of these are missing, they should be marked as unknown on the schematic rather than filled in with empirical values.
Conclusion
INIC6711 can be accurately summarized as: performing active protocol bridging between a normal SATA Host and a SAS Drive.
It requires at least:
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The K308SAS and BS-HD01S teardowns provide strong evidence for the chip identity and typical support circuitry. ADPTSAS-L01 VER006 demonstrates a pure single-drive SASโSATA design, but its sanded-off controller can only be described as highly likelyโnot confirmedโto be INIC6711.
The difficulty of this solution is not the SFF-8482 interface, but the QFN-64 pinout, power sequence and external SPI Flash firmware.
In the absence of a complete datasheet, the most reliable route is to start from the normal physical object: first back up the firmware, measure the power supply, confirm the crystal oscillator, and then map the high-speed lines and low-speed control signals.
Successful bridging does not mean obtaining full SAS capabilities. Dual ports, multipathing, SCSI management, protection information, and some health data may be hidden by the SATA presentation layer.
Therefore, INIC6711 is more suitable for single disk access and hardware research; when involving critical data, 520/528 byte formats or production environments, standard SAS HBA remains the lower risk option.
References
- Maiwo K308SAS Teardown: INIC6711, INIC3639, 25MHz and 4Mbit Flash
- ADPTSAS-L01 type SASโSATA active adapter disassembly and testing
- XTX XT25F04B 4Mbit SPI Flash information
- [Marvell SAS-to-SATA Protocol Converters: An enterprise storage case in the opposite direction] (https://www.marvell.com/products/system-solutions/sas-to-sata-protocol-converters.html)