One thing I really dislike is slow portable storage. While many manufacturers continue to pump out smaller and smaller USB flash drives at ever diminishing price points, one thing that never seems to satisfy is their performance. Even with advertised USB 3.0 interfaces, such no-frills drives often have 10-30MB/s write speeds owing to their “cheap” single-channel TLC designs. Further to that, TLC reliability can be a problem – I’ve had three USB keys under heavy read/write loads decide to “pack up” and die in a read-only/drop-out style mode.
In the quest for better portable storage which was more robust than USB keys, I turned to putting SSDs in external enclosures in early 2013 with fairly good results as well as some warnings due to the unusual workload which can involve unexpected power-downs. As SSDs continued their slow march to better value, I continued on with this practice, noting that different bridge chips and different SSD controllers have different behaviours in a “TRIM-less” environment. The one thing that always impressed me was the performance – it was unlike any external hard drive or USB flash drive I had ever used. In the worst case, however, things could become really bad, resulting in very slow performance, so over-provisioning seemed to be the way around it and did the trick.
As it seems, my gripes about USB storage devices didn’t go unnoticed, with quite a few visitors to those pages by like-minded people seeking a better storage solution. Companies soon came out with their own products which emulate a similar promise in a more compact form factor – say the Samsung T1 series, the Transcend ESD400 series, and various others from manufacturers who claim them to be SSDs but in form factors more resembling USB keys. The one thing that these devices had in common was high cost, making them less attractive to me.
This changed, when Kogan advertised the Lexar Professional Workflow DD512 (512Gb) USB 3.0 Storage Drive on special on 2nd September (not anymore though). It was listed at a price that led me to pay AU$190.99 including shipping and insurance. That worked out to be a crazy low AU$0.373/Gb. Despite having problems with Lexar products recently, I decided that the price was just too good to pass up on. After all, Kogan claimed to be an authorized distributor, and Lexar was a brand of high repute amongst professional photographers. Maybe the “professional” name indicates a better product?
Many people must have jumped on the deal at the time, as Kogan was having trouble fulfilling orders on time. I got an e-mail claiming there was a delay, with a new expected shipping date which they also missed. In the end, I tried chasing them up by phone, but their phone menus weren’t working. I then chased them up by live-chat, only to be told to wait for an e-mail, which was a canned response with no substance. In the end, the product arrived on 22nd September, 20 days after ordering.
The Lexar Professional Workflow DD512 (or “workflow” from now on) is a 512Gb USB 3.0 connected SSD. It came packaged in a folded, clear-plastic box, showing off the drive in the front. The drive is specified at 450MB/s read and 245MB/s write according to “internal testing” which is relatively decent for a USB 3.0 connected device. The design of the drive is specific, so that it can be used in the relatively pricey Lexar Workflow HR1/HR2 storage reader hubs, which provide slots where different modules of SSDs and card readers can be docked into. Despite this, the drives can also be used standalone without the HR1/HR2 hubs.
The unit has a model number of LRWDD512CRBNA and is Made in China. One of the features of the drive is an array of LEDs on the front, visible through the plastic, that indicate activity (one blue, right-most) and capacity used (five white).
The unit claims compatibility with Mac OSX 10.6 +, Windows 7 and 8 and USB 2.0 and 3.0 ports. I technically see no reason why the drive isn’t compatible with Windows 10, or various flavours of Linux, etc. The package is fairly spartan, with just the drive and a USB 3.0 cable being included.
A departure from the norm is seen, with the use of the full size USB 3.0 “B” style connector which is rarely seen in devices other than hubs and docks. Despite its large size, it has a strength of being relatively robust, although it’s less likely you will have a spare cable on-hand though. It was probably chosen due to robustness for docking with the HR1/HR2 hub.
The drive is black in colour, in a multi-textured molded plastic enclosure measuring 7.5cm x 6cm x 2.2cm, making it smaller than a 2.5″ enclosure by a substantial amount. It weighs a relatively light 62 grams, drive only.
The underside claims that this product is a Revision A, meaning it’s likely to be an early product. The unit has a nice rubberized “ring” foot which helps keep it somewhat steady on a table, although the stiffness of the USB cable seems to compete with this somewhat.
The unit itself is less compact than other USB 3.0 SSDs on the market due to the “integration” with the Lexar HS1/HS2 hubs, and is thus, less appealing to those looking for ultimate portability. But what is it made of? Is there an M2/mSATA card hiding inside? Lets find out!
The drive itself is made using a screw-less design. Prying off the back cover can be achieved with a pair of flat-head screwdrivers and some care.
Removing the PCB is a bit of a task however, as it is thermal-pad connected to the rear plastic. This is a very crude method of trying to expel heat from the plastic “box”, but because of the low thermal conductivity of the plastic, it seems this is a relatively ineffective heatsink. However, it probably does get rid of just enough heat to keep the NAND chips from being cooked.
The PCB inside is a chocolate brown coloured affair, with the NAND and requisite controllers all mounted firmly on the board. Those hoping for a cheap M.2 or mSATA board are out of luck.
The solution is for all practical intents a SATA SSD and a USB 3.0 to SATA bridge chip hooked together. Specifically, this solution uses the Asmedia ASM1053 UASP capable USB 3.0 to SATA bridge chip (Week 52, 2013) and a Silicon Motion SM2246XT SATA III SSD controller (Week 21, 2014). This is, in essence, the slightly slower DRAM-less brother of the SM2246EN which I have previously used in the Kingmax SME35 Xvalue SSD which has performed just fine.
Looking at my old photos of ASM-based bridge boards, it seems that the SATA connections from the SM controller to the ASM controller are made where C5, C6 are for the first pair, and C7, C8 are for the second pair. Should there ever be a need for data recovery where the bridge chip had failed, it seems possible to desolder C5, C6, C7, C8 and solder SATA cable conductors directly to the pads on the SM side.
Two flash chips can be seen on the top side, along with some power regulation circuitry. The flash chips are marked PFH02-10AL, dated Week 18 of 2014. From the Spectek decoder, these are the FBML85AA1KDUABH8-10AL chips, specified as 128Gx08 CE=4,PLANE=2,BLK=4096,PG=512,BYTE=17552 LBGA 152-ball 3.3V/1.8V.
Seeing the drive advertised as “by Micron” and seeing Spectek parts inside might feel a little sad, as Spectek began as a “component recovery” division of Micron, generally dealing with parts that weren’t good enough to be marked with the Micron name. However, these parts are marked with the bin code of 10AL, which is Spectek’s highest grading, meeting full specifications with ~95% good blocks. I do, however, think that Micron branded flash may indeed be slightly better, but in the end, they did tell the truth.
Four BGA footprints remain unoccupied, which will allow for the drive possibly to be made with half-density (64Gx8) parts, or maybe for a 1Tb model to be made provided the controller can handle it.
The underside contains two more flash chips, some more power regulation hardware and (likely) a serial EEPROM with the configuration data for the controller. The PCB is dated Week 39 of 2014. Remnants of the thermal pad can be seen on the side of the flash chips, as I yanked it out of the case, and the sharp edges of the chips have “planed” off some of the thermal padding.
The drive was reassembled without injury, however, the effectiveness of the thermal padding may have been slightly compromised. As a result, I do not advise users to disassemble their drives – there appears to be no reusable parts.
When connected to a computer, it is detected as a Lexar WorkflowD512 USB Device. Under Windows 8 and above, it is detected as a UASP capable storage device which will provide better performance for those systems. The VID is 05DC and the PID is BA0A.
It is detected as a “removable disk” rather than a fixed disk, and comes pre-formatted with exFAT. A total of 512,092,012,544 bytes exist in the drive with the default factory formatting with a volume label of D512.
The drive can be reformatted, and reformatting to NTFS has the drive show a capacity of 512,108,785,664 bytes in total, although more space is taken by the file-system as reserved.
A test with trimcheck shows indeterminate results under exFAT and not working under NTFS, which has me believing that TRIM is not functioning. It seems that trimcheck run on other USB keys formatted with FAT/FAT32/exFAT turn up as indeterminate as well when I have tested it.
As the drive is typed as a Removable Disk, no doubt due to a special configuration of the Asmedia bridge chip, SMART data checking using CrystalDiskInfo does not work. It seems that either the software, or Windows, does not pass the required commands to the drive. That being said, under Linux, smartctl will not deal with the drive by default, but if you add the -d sat option to the command line to use “SCSI ATA translation (auto)” then the SMART queries do make it through the bridge. The full data is listed in the Appendix at the end of the article.
Device Model: SILICONMOTION SM2246XT LU WWN Device Id: 0 000000 000000000 Firmware Version: 20150209 User Capacity: 512,110,190,592 bytes [512 GB] Sector Size: 512 bytes logical/physical Rotation Rate: Solid State Device ATA Version is: ACS-2 (minor revision not indicated) SATA Version is: SATA 3.1, 6.0 Gb/s (current: 6.0 Gb/s) SMART support is: Available - device has SMART capability. SMART support is: Enabled AAM feature is: Unavailable APM feature is: Unavailable Rd look-ahead is: Disabled Write cache is: Enabled ATA Security is: Disabled, NOT FROZEN [SEC1] Wt Cache Reorder: Unavailable
I’ve removed some information, namely the serial number and date time from this “trimmed” section, but it’s interesting to note that the device model concurs with that of the teardown, but the actual device ID is not customized and comes up as SILICONMOTION SM2246XT implying that it’s running a firmware build which may be as supplied by them with minimal customization. The firmware version appears to be a date – a recent one at that – 9th February 2015.
During testing, the drive performed normally with no problems on both test configurations. The drive did, however, get somewhat warm but only on the bottom side. This is expected due to the discovery of a thermal pad only on the bottom of the PCB, although using a plastic case as a heatsink is unlikely to bring good results.
With NEC Renesas Chipset on Gigabyte 890FXA-UD7 and Windows 7
While this configuration is a little long in the tooth, it’s the configuration used for practically all the flash testing to date, so getting a baseline on this configuration will show you the lower-bound of expected USB 3.0 non-UASP add-in card chipset based performance.
HD Tune readback achieved an average of just shy of 256MB/s – not a bad effort at all.
Under CrystalDiskMark, the drive achieved just shy of 270MB/s in read and 200MB/s in sequential writes. This is shy of the 450MB/s and 245MB/s claimed on the box, however, it is important to note that this result is without UASP. Compared to my former Sandforce based experiments, this drive was faster sequentially (191MB/s read and 166MB/s write), however, in the small block accesses, the Sandforce was significantly faster (20.05MB/s read, 43.87MB/s write). This probably comes down to the DRAM-less SM2246XT’s limitations.
The drive showed just 165MB/s write and 215MB/s read under H2testW’s sustained full-drive workload. This may be because of slow-downs as flash becomes full due to a lack of overprovisioning, and possible CPU limitations in verifying the data. At least the test was passed with no failures.
With Intel USB 3.0 Chipset on Lenovo Thinkpad Edge E431 and Windows 10
This configuration is a more modern laptop with integrated USB 3.0 chipset, from the Intel camp. As it runs Windows 10, it has UASP capabilities and is more likely to come close to fully exploiting the capabilities of USB 3.0 connected SSDs.
Under the Intel controller, the average read rate was 347.6MB/s, still quite a way away from the 450MB/s claimed on the box. It did peak at 409.1MB/s but only transiently.
This result is concurred by the CrystalDiskMark results, showing sequential read of 348MB/s and write of 249MB/s. At least the write speed, sequentially, was shown to exceed the 245MB/s claimed on the box. The small block performance still remains poorer than that of my previous SSDs-in-an-enclosure, even with command queueing, the improvements remain slim to none. This suggests that the SM2246XT really isn’t great at small block access – noting that with UASP, tests with a Jmicron based Transcend SSD340 were able to achieve 121.7Mb/s read and 144.6Mb/s write with UASP in 4k QD32 mode.
H2testW was passed with only minor speed improvements over the non-UASP mode of operation.
The Lexar Professional Workflow DD512 512Gb USB 3.0 storage drive is definitely an interesting product. Built from a Silicon Motion SM2246XT “value” SSD controller connected back-to-back with an ASmedia ASM1053 UASP SATA to USB 3.0 bridge chip, it emulates putting a SATA SSD in an enclosure in a more compact and integrated way. Performance is very similar to what you would expect from such a configuration, which will vary depending on your USB 3.0 controller and driver stack. In all, the performance was reasonably good, although with small block accesses, it seems that the IOPS limitations in the DRAM-less SM2246XT began to show especially in small block accesses where performance was less than stellar and UASP did not seem to improve the results. Some of my other low-cost drives in enclosures were able to achieve four to ten times the small block performance (4k QD32).
This drive has a quirk, namely that it is configured to be a Removable Disk (to emulate USB keys) rather than a fixed disk, and this means that Windows treats it slightly differently in partitioning and in SMART access. smartctl under Linux requires the addition of a device type argument to see the SMART data. As a result, it is less convenient to diagnose the state of your SSD and determine its health. Also, SiliconMotion’s SMART attributes are not widely understood at this time, thus interpreting the SMART data is also difficult.
Despite this, at the price I paid for it, it was a really compelling buy, and I wish I had purchased more. It does work well for bulk transfers, and the use of a value SSD chipset reduces the cost and is generally a better match for USB 3.0, which in itself, isn’t particularly high performance compared to SATA III. At the present price of AU$249, however, it is less of a bargain although probably still worthy of consideration, although users wanting more compact solutions should probably look elsewhere (e.g. Samsung T1, Transcend ESD400).
Appendix: smartctl Output
smartctl 6.2 2013-07-26 r3841 [x86_64-linux-3.13.0-61-generic] (local build) Copyright (C) 2002-13, Bruce Allen, Christian Franke, www.smartmontools.org === START OF INFORMATION SECTION === Device Model: SILICONMOTION SM2246XT Serial Number: [removed] LU WWN Device Id: 0 000000 000000000 Firmware Version: 20150209 User Capacity: 512,110,190,592 bytes [512 GB] Sector Size: 512 bytes logical/physical Rotation Rate: Solid State Device Device is: Not in smartctl database [for details use: -P showall] ATA Version is: ACS-2 (minor revision not indicated) SATA Version is: SATA 3.1, 6.0 Gb/s (current: 6.0 Gb/s) Local Time is: Tue Sep 22 22:19:58 2015 AEST SMART support is: Available - device has SMART capability. SMART support is: Enabled AAM feature is: Unavailable APM feature is: Unavailable Rd look-ahead is: Disabled Write cache is: Enabled ATA Security is: Disabled, NOT FROZEN [SEC1] Wt Cache Reorder: Unavailable === START OF READ SMART DATA SECTION === SMART overall-health self-assessment test result: PASSED General SMART Values: Offline data collection status: (0x00) Offline data collection activity was never started. Auto Offline Data Collection: Disabled. Total time to complete Offline data collection: ( 0) seconds. Offline data collection capabilities: (0x00) Offline data collection not supported. SMART capabilities: (0x0002) Does not save SMART data before entering power-saving mode. Supports SMART auto save timer. Error logging capability: (0x00) Error logging NOT supported. General Purpose Logging supported. SMART Attributes Data Structure revision number: 1 Vendor Specific SMART Attributes with Thresholds: ID# ATTRIBUTE_NAME FLAGS VALUE WORST THRESH FAIL RAW_VALUE 1 Raw_Read_Error_Rate ------ 100 100 050 - 0 5 Reallocated_Sector_Ct -O---- 100 100 050 - 0 9 Power_On_Hours ------ 100 100 050 - 3 12 Power_Cycle_Count ------ 100 100 050 - 13 160 Unknown_Attribute ------ 100 100 050 - 0 161 Unknown_Attribute ------ 100 100 050 - 117 162 Unknown_Attribute ------ 100 100 050 - 1 163 Unknown_Attribute ------ 100 100 050 - 15 164 Unknown_Attribute ------ 100 100 050 - 4791 165 Unknown_Attribute ------ 100 100 050 - 4 166 Unknown_Attribute ------ 100 100 050 - 2 167 Unknown_Attribute ------ 100 100 050 - 2 192 Power-Off_Retract_Count ------ 100 100 050 - 0 194 Temperature_Celsius ------ 100 100 050 - 37 195 Hardware_ECC_Recovered ------ 100 100 050 - 615 196 Reallocated_Event_Count ------ 100 100 050 - 0 199 UDMA_CRC_Error_Count ------ 100 100 050 - 0 241 Total_LBAs_Written ------ 100 100 050 - 36127 242 Total_LBAs_Read ------ 100 100 050 - 78791 ||||||_ K auto-keep |||||__ C event count ||||___ R error rate |||____ S speed/performance ||_____ O updated online |______ P prefailure warning Read SMART Log Directory failed: scsi error aborted command ATA_READ_LOG_EXT (addr=0x00:0x00, page=0, n=1) failed: scsi error aborted command Read GP Log Directory failed SMART Extended Comprehensive Error Log (GP Log 0x03) not supported SMART Error Log not supported SMART Extended Self-test Log (GP Log 0x07) not supported SMART Self-test Log not supported Selective Self-tests/Logging not supported SCT Commands not supported Device Statistics (GP Log 0x04) not supported SATA Phy Event Counters (GP Log 0x11) not supported