by Larry Sabo, 2019-03-14
The DeepSpar USB Stabilizer is a pass-through device that isolates USB drive instability from Windows. I was provided with a beta version of the Stabilizer for testing and review.
The features, benefits and principles of operation of the USB Stabilizer are outlined on the DeepSpar website. Rather than repeat that information here, I would like to address its appeal to me as a DFL user, and review how it performed in my testing.
Its Appeal to Us
When unstable drives are accessed by Windows, they frequently drop off-line whenever data cannot successfully be read from the drive within a timeout period. The drive might or might not come back on-line after some delay or Windows might freeze and require a hard reboot. This instability makes it difficult to use Windows-based data recovery software directly on such drives with any confidence.
Our normal procedure for recovering data from unstable drives is to clone or image the drive using a hardware-based imager that handles the drive’s I/O directly and feeds the data to Windows. Windows-based data recovery software can then work on the data without being affected by the instability.
We use Dolphin Data Lab’s SRP data recovery tool and its Windows-based DFL-DE program to clone and image drives. Unfortunately, the DFL SRP does not incorporate a USB port, so it’s impossible to directly connect USB drives to the DFL to isolate them from Windows. It does enable access to USB drives that are connected to Windows, but if the drive is unstable and drops off-line or causes Windows to freeze, that’s not much help. Enter the DeepSpar USB Stabilizer. It connects between the USB drive and the PC’s USB port, isolating the instability from Windows.
SATA Adaptation and Conversion
The DFL (like most data recovery tools) is designed to work directly with SATA drives, rather than USB drives. This is because the SATA interface enables use of more comprehensive and effective ATA commands, rather than the limited set of vendor-specific commands that are able to traverse the USB interface.
Without the USB Stabilizer, we normally effect SATA access by swapping the drive’s USB PCB with a compatible SATA PCB. That requires transferring the ROM then repairing any firmware problems, cloning or imaging the drive, and recovering the data from the clone. For DFL users dealing with highly unstable USB drives, transferring the ROM requires it to be unsoldered, read with an external programmer, then written to the SATA PCB. When the recovery is completed, the ROM is usually reattached to the USB PCB.
If a compatible SATA PCB is not available, we modify the USB PCB to enable SATA access by removing a few capacitors and soldering leads between a SATA data connector and specific vias on the USB PCB. It requires meticulous micro-soldering and occasionally some research.
Adaptation and conversion take time and there is the risk of losing, damaging or corrupting the ROM, or damaging the PCB. Some USB PCBs simply cannot be converted to SATA and don’t have a SATA equivalent. In such cases, the Stabilizer could prove invaluable.
There is also the matter of encryption. Most Western Digital USB drives utilize an IC on the PCB to encrypt the data before it is written to the platters and decrypt it when it is read back. However, the DFL software incorporates decryption capability, so extracting decrypted data from the SATA clone or image is not usually a problem. Where decryption by DFL it is not possible, the patient’s USB PCB can be attached to the clone to access the data in decrypted form, assuming it is healthy and physically compatible with the clone. Being able to read decrypted data directly from USB drives eliminates the need to decrypt the data since it is decrypted by the USB PCB as it is read.
The option to clone unstable USB drives and access the data in decrypted form, without going through SATA adaptation or conversion, is very appealing.
USB Stabilizer Control Panel
The Control Panel is the Stabilizer’s user interface and includes Settings, Log and Sector Map panes, as well as a context pane that can be displayed by right-clicking the title bar, as shown below. View the DeepSpar demo video for descriptions of the alternative settings (which settings are fully described in the Help documentation). The Control Panel settings shown below were used for all of our tests. Allow SCSI Pass-Through was enabled because otherwise the DFL could not access the USB drive, and although not required, was also used with the other recovery programs tested, for comparability.
Test Procedure and Results
We selected an unstable USB drive and connected it to the Stabilizer, which we connected to the PC. A particularly unstable 300,000 sectors were imaged with and without the USB Stabilizer using DFL-DE, R-Studio, Recovery Explorer and DMDE.
Here is a video of the DFL imaging the selected sectors with the Stabilizer…
… and below is a video of the DFL imaging the same sectors without the Stabilizer…
The videos were created by specifying the sector range to be imaged (sectors 54.0M – 54.3M), starting imaging and then, within a couple of seconds, stopping imaging. The DFL doesn’t stop immediately; it creates the front end of the image, filling it with zeros, then stops. The zero-filling process stops just after the 54.0M sectors are written but the over-run is minor and not significant. After imaging is resumed and completed, the DFL log shows the start and completion times for imaging the sectors of interest, i.e., LBAs 54.0M to 54.3M.
Below is a summary of the times taken to image the selected sectors using the recovery programs mentioned.
With more experience, imaging times could probably be reduced once one learns which reset options should be tried when the drive exhibits a particular behaviour. The Guardonix write blocker and stabilizer, a simplified and less expensive version of the Stabilizer built for forensic investigators, offers automatic escalation/de-escalation of the reset method depending on the changing need for more or less aggressiveness, rather than discrete choices data recovery specialists would prefer. (Adding Automatic as a reset option could be helpful, especially if it displayed the reset method as it changes in real time.)
All programs obviously benefited greatly from the stability provided by the USB Stabilizer.
Although its primary mission is to deal with USB drives, the Stabilizer can also deal with SATA drives mounted in a USB drive dock or connected to a USB adapter. When we initially had difficulty finding a suitable USB drive for tests, we decided to use a SATA drive in a USB dock to simulate the behavior of a USB drive.
We selected a WD laptop drive (Mariner), mounted it in a drive dock connected directly to a PC USB port and tried to access it using the DFL. Because it was very unstable, it locked up Windows completely on the first PC we tried, requiring the PC to be forcefully rebooted. On a second PC, it became unresponsive after a few seconds and never became accessible during the 15 minutes we waited. Repowering the USB dock caused the DFL to resume reading but skip every sector.
Next, we connected the USB Stabilizer in-line with the drive dock and tried the same drive again. After about 20 seconds, the reading and cloning began and continued without locking up Windows. Cloning was greatly delayed when read errors occurred but proceeded at a brisk clip otherwise. Such delays were reduced to seconds each by a subsequent Stabilizer firmware update.
Being able to use the Stabilizer with USB docks and adapters would be helpful should the DFL become temporarily unavailable or when there is a backlog of imaging jobs.
The USB Stabilizer can also be used with PCIe-interfaced SSD drives when mounted in a PCIe-USB adapter but we did not test this capability. A set of various adapters can be purchase with the USB Stabilizer.
Firmware Repair, Selective Head Imaging and Physical Damage
We had no problem reading, editing and saving ROM and modules and imaging data-only sectors of drives accessed through the Stabilizer. However, the DFL was unable to do selective head imaging through USB. I understand it is a problem limited to the DFL and that PC-3000 and MRT tools don’t have that limitation. If selective imaging by head is necessary, SATA adaptation or conversion would be required when using the DFL. Perhaps a future DFL update will address that limitation.
For drives that have been dropped or that make strange noises, it is imperative to examine the heads in a cleanroom environment for damage or signs of media damage before attempting to clone the drive. However, the Stabilizer can still be put to effective use once heads are swapped, should that be required.
The Stabilizer was very effective at isolating a highly unstable USB drive from Windows so the DFL could repair firmware and clone the drive for data recovery without requiring a SATA PCB swap, SATA conversion, or decryption after cloning. That can enhance the DFL’s usefulness, reduce the risk of damaging or corrupting the ROM, save time and effort, and improve recovery turn-around times.
I’d like to thank Serge Shirobokov from DeepSpar for providing the Stabilizer and the opportunity to test and review it.