Discreet Quality: Review of the sketchiest-looking 512GB Lexar SDXC card

It’s amazing how much Flash-based storage technology has advanced in the last few years, especially considering how much prices have dropped.

Naturally, when it comes to speed, capacity and price, consumers tend to look for the lowest price; as manufacturers race towards the bottom line, many will take the low road and sell counterfeit goods. This is especially prevalent in the NAND Flash market, and online marketplaces like eBay, AliExpress and even Amazon are fraught with countless fake storage devices that claim high capacities at too-good-to-be-true prices. It’s not uncommon to see unrealistic capacities sold for a few tens of dollars, but what the customer ends up receiving is a storage device with a falsified capacity that will pass a simple copy-paste test but will corrupt itself with extended use.

While browsing eBay for some deals on some Flash storage, I happened upon a very strange-looking 512GB SDXC card. It was listed as an OEM Lexar card but had no labels, selling for an unprecedentedly low price of $60 USD (the card would cost several times more at normal retail outlets). On the outside, everything about the card’s exterior seems to raise a red flag that the card is not to be trusted.

Lexar OEM 512GB Listing

eBay listing of the Lexar OEM 512GB SDXC card

Upon closer inspection, there are some hints that one shouldn’t always judge a book – er, card – by its cover. The laser-etched markings might look like cryptic gibberish to the layperson, but the markings “SM2702BAC” and “L95B” have actual meanings; the SM2702 is an SD card controller by Silicon Motion, and L95B refers to the 16nm generation of MLC NAND Flash by Micron, which owns the Lexar brand (but unfortunately is being discontinued). The seller also says that the cards have been tested, which is reassuring.

I decided to take the plunge and plunk down about $80 USD including shipping (or $105 CAD at the time) and buy a card for myself.

A Closer Look

After waiting a few weeks, the card showed up in my mailbox. The seller did a very good job packaging it, even placing the card in an ESD shielding bag before wrapping it with foam and placing it in a bubble mailer (it’s much better than the plastic wrap I’ve had some used i7 CPUs by a huge amount).

 

The card looks very plain, with the top label area lacking any labeling, and the same laser-etched markings on the back. The card’s contacts indicate that it has been placed in a card reader a few times before (presumably for testing).

Card Identification

I used my old Gateway M-7305u laptop with Kali Linux to see what information the card reports. These older laptops have true SDA (SD Association) compliant card slots, so they will identify as an actual SD card instead of a USB drive like with many modern laptops; in Linux these show up as devices like /dev/mmcblk0 instead of /dev/sda. By using the “dmesg -wH” command I can read the kernel logs once the card is connected to the computer.

[Jan24 10:52] mmc0: new high speed SDXC card at address 59b4
[ +0.094917] mmcblk0: mmc0:59b4       483 GiB 
[ +0.001111] mmcblk0: p1

The card reports a capacity of 483 GiB (that’s binary gigabytes, or 519.6 decimal – a.k.a. “weasel” – gigabytes), but the SD card name is ”     ” – five ASCII spaces. Everything about the card superficially rings alarm bells! However, I wasn’t phased, and decided to try the card in my Kingston FCR-HS4 USB 3.0 card reader, which uses the Realtek RTS5321 chipset.

Lexar OEM 512GB Partition

OEM Lexar 512GB SDXC card in Disk Management

Examining the card in Windows shows that the card was formatted as exFAT with a drive name of “SDXC”, suggesting it may have been formatted by the seller with the SD Formatter tool. Looking at the raw sector data in Hard Disk Sentinel suggests that the seller indeed do a full capacity test, as the data patterns match that of the program H2testw, an excellent tool for detecting fake Flash memory. This is a good sign – the seller did their due diligence and by this point I already had a good feeling that the card is genuine.

However, I wanted to test this for myself, so I ran the H2testw utility myself and let it run on the card. The write speed remained consistent throughout, which is a good indication that the card is not overwriting memory locations like in fake Flash storage (the card did get uncomfortably hot during the process, however). It took four hours to complete the write and read test, but everything came out clean – the card is genuine, even when every other sign says otherwise!

Lexar 512GB OEM H2testw

H2testw verifying that the OEM Lexar card’s 512GB capacity is genuine

Performance

With the card verified, it was time to put it to the test.

CrystalDiskMark

The card showed sequential read speeds of 92.03 MB/s and sequential write speeds of 60.45 MB/s; the sequential write speed coincides with the seller’s rating of 400x (400 * 150 kB/s = 60 MB/s).

The random 4K I/O performance isn’t great, especially with writes, but it isn’t bad either. The card managed 4K random read speeds of 6.644 MB/s (1700.9 IOPS) and 4K random write speeds of 0.671 MB/s (171.8 IOPS).

Lexar 512GB OEM Benchmark

Benchmark of the 512GB Lexar OEM SDXC card in CrystalDiskMark 3.0.4

Conclusion

In the end, I was satisfied – I got a 512GB SDXC memory card at a fraction of the cost from a normal retail outlet. It’s not exactly a speed demon, but it’s not a slowpoke either. The looks may be deterring for most folks (and rightly so), but with the right tools and knowledge, one can pick up one of these less aesthetically-pleasing memory cards and save some serious coin in the process.

Advertisements

eMMC Adventures, Episode 1: Building my own 64GB memory card with a $6 eMMC chip

As seen on Hackaday!

There’s always some electronics topic that I end up focusing all my efforts on (at least for a certain time), and that topic is now eMMC NAND Flash memory.

Overview

eMMC (sometimes shown as e.MMC or e-MMC) stands for Embedded MultiMediaCard; some manufacturers create their own name like SanDisk’s iNAND or Hynix’s e-NAND. It’s a very common form of Flash storage in smartphones and tablets, even lower-end laptops. The newer versions of the eMMC standard (4.5, 5.0 and 5.1) have placed greater emphasis on random small-block I/O (IOPS, or Input/Output operations per second; eMMC devices can now provide SSD-like performance (>10 MB/s 4KB read/write) without the higher cost and power consumption of a full SATA- or PCIe-based SSD.

MMC and eMMC storage is closely related to the SD card standard everyone knows today. In fact, SD hosts will often be able to use MMC devices without modification (electrically, they are the same, but software-wise SD has a slightly different feature set; for example SD cards have CPRM copy protection but lack the MMC’s TRIM and Secure Erase commands. The “e” in eMMC refers to the fact that the memory is a BGA chip directly soldered (embedded) to the motherboard (this also prevents it from being easily upgraded without the proper tools and know-how.

Continue reading

Review of SanDisk Extreme CompactFlash 32GB (SDCFXS-032G)

After my previous review of a Silicon Power 8GB CompactFlash memory card, I was looking around for more CF cards to review, in the hopes of finding a higher-performing card with S.M.A.R.T. health reporting and the ability of acting as a “fixed disk” (that is, identifying to the system as a hard drive rather than a removable disk), and decided to purchase this memory card from Amazon.

Advertised specifications

The card’s specifications indicate that the CompactFlash card is capable of 120MB/s sequential read and 60MB/s sequential write speeds, has a lifetime warranty and comes with a license key for a 1-year subscription to their RescuePRO data recovery software. It is advertised to have internal RTV (room-temperature vulcanization) silicone potting, has an operational temperature range of -25 to 85 degrees Celsius (-13 to 185 Fahrenheit), and uses their “ESP (Enhanced Super-Parallel) Technology” which I presume is some sort of proprietary multi-channel controller, and is UDMA 7 (167 MB/s maximum interface speed) capable.

Benchmark – Setup

To connect the card to my computer, I used a CompactFlash-to-IDE converter and a Marvell 88SE9128-based SATA/PATA host bus adapter. This allows me to use up to UDMA 6 (133 MB/s maximum interface speed) as UDMA 7 is basically restricted to cameras as it’s only part of the CompactFlash official specifications.

Benchmark – CrystalDiskMark

For this test, I manually zero-filled the card using Hard Disk Sentinel, formatted it with exFAT, then ran CrystalDiskMark, set to 3 runs with a 500MB file size using random data, all zeros (0x00), and all ones (0xFF).

Data Type Test Read (MB/s) Write (MB/s) IOPS Read IOPS Write
Random Sequential 103.2 52.45
512K Random 99.55 29.57
4K Random (QD1) 11.37 0.916 2775.2 223.6
4K Random (QD32) 17.24 1.413 4208.2 344.9
All 0 (0x00) Sequential 104.3 54.25
512K Random 98.27 31.22
4K Random (QD1) 11.36 1.1 2773.3 268.5
4K Random (QD32) 17.39 1.263 4244.5 308.4
All 1 (0xFF) Sequential 104.5 53.95
512K Random 98.05 25.84
4K Random (QD1) 11.19 1.112 2733 271.4
4K Random (QD32) 17.32 1.437 4229.3 351

It appears that there is no significant difference between the tests depending on what data was used for the benchmark.

Benchmark – AS SSD

As with CrystalDiskMark, I zeroed out the card and formatted it as exFAT before running the test.

Test Read Write
Sequential 99.70 MB/s 46.13 MB/s
4K 11.40 MB/s 0.74 MB/s
4K 64 Thread 12.80 MB/s 1.03 MB/s
Access Time 0.389 ms 5.504 ms
Score 34 6
61

Benchmark – Hard Disk Sentinel

I ran three separate benchmarks with Hard Disk Sentinel’s Surface Test feature, using the read and write (both empty and random data) tests, and used the Random Seek Test to measure the card’s responsiveness after filling it with empty and random data.

Test Speed
Read 0x00 95.20 MB/s
Read Random 97.30 MB/s
Write 0x00 49.81 MB/s
Write Random 49.04 MB/s
Seek Time 0x00 0.35 ms
Seek Time Random 0.37 ms

Once again, there does not appear to be any appreciable difference between an empty (zeroed-out) or full card.

Analysis – HWiNFO64

Now that the benchmarks are out of the way, let’s take a look at the card and what it can (and can’t) do. Let’s take a look at the details of the drive…

The card shows up as a regular IDE drive in HWiNFO, and has information about its CHS (Cylinder-Head-Sector) geometries and supported I/O interface speeds. Here we can see the card supports up to UDMA 7 but is running at UDMA 6 as because it is connected to a PC IDE bus.

Now for the kicker: Does the drive identify itself as a fixed or removable disk? Cross your fingers…

NOPE! The SanDisk Extreme CompactFlash card does NOT identify as a fixed disk, but instead as a removable drive. This means that the hopes of using this as a bootable Windows disk are now out the window. [ba-dum-tssh!]

Analysis – Hard Disk Sentinel

Looking at the Overview tab in HDS, something weird is happening. It states that “the hard disk status is PERFECT” yet it has no health or performance percentages available. If I open the Information tab, I can see that the SanDisk Extreme CompactFlash card does NOT support S.M.A.R.T. health reporting. Bummer. Additionally, it appears that Windows does not like removable IDE drives that lack S.M.A.R.T. and instead report garbage data (or data mirrored from another drive in the system).

Looking further inside the Information tab, we can see the features that the memory card does support. It supports DMA, Ultra DMA, APM (advanced power management), write caching, 48-bit LBA (logical block address) addressing, IORDY (flow control), a NOP (no-operation) command, and has the CFA (CompactFlash Association) feature set.

Since the card reported that it supported APM, I tried to enable it but the card refused to accept the command.

Conclusion

Overall, I like this card quite a bit. It has fast sequential I/O and a respectable random read speed. However, this is soiled by the fact that the card is configured to show up as a removable disk, which renders the card unusable as a Windows boot drive, and the lack of S.M.A.R.T. health and temperature reporting makes me a bit uneasy as I cannot track the card’s program-erase cycle count during use.

Oh well. Looks like the hunt for a fast, fixed-disk CompactFlash card continues…