SanDisk Ultra 128GB

  • Obtained from: AliExpress
  • Price paid: $14.58
  • Advertised capacity: 128GB
  • Logical capacity: 127,865,454,592 bytes
  • Physical capacity: 127,865,454,592 bytes
  • Fake/skimpy flash: Skimpy (0.11% skimp)
  • Protected area: 134,217,728 bytes
  • Adjusted skimp: 0.00026%
  • Speed class markings: Class 10, U1*, A1
  • CID data:
    • Manufacturer ID: 0x03**
    • OEM ID: 0x5344 (ASCII: SD)**
    • Product name: 0x5344313238 (ASCII: SD128)
    • Product revision: 0x85
Sample #123Average
Manufacture dateDec 2023Dec 2023Aug 2023N/A
Serial number0x545a014f0x5399d2390x92dccb2bN/A
Sequential read speed (MB/sec)162.28173.54151.13162.32
Sequential write speed (MB/sec)30.0931.7231.6031.14
Random read speed (IOPS/sec)2,300.372,345.092,060.452,235.30
Random write speed (IOPS/sec)528.90526.42446.88500.73
Read/write cycles to first errorNot yet determinedNot yet determinedNot yet determinedNot yet determined
Read/write cycles to complete failureNot yet determinedNot yet determinedNot yet determinedNot yet determined
Total days to complete failureNot yet determinedNot yet determinedNot yet determinedNot yet determined
Package frontN/A
Package backN/A
Card frontN/A
Card backN/A

* The U1 mark appears on the card, but does not appear on the product packaging.

** This manufacturer ID/OEM ID is pretty well known to be associated with SanDisk.


I believe I picked up this one after seeing that SanDisk advertised performance differences between the 32 and 64GB versions of both the Extreme and the Extreme Pro, and I wondered if larger sizes of the SanDisk Ultra would show similar performance improvements when compared to its smaller siblings.

As it turns out, the answer was “yes”: this card did significantly better in sequential read speeds, and mildly better in sequential write speeds, than the SanDisk Ultra 32GB. Random read speeds were worse than the 32GB version, while random write speeds were about the same. Overall, two of the three samples got sequential read speeds that were more than two standard deviations above average, while the third came close. Sequential write speeds were right around average, and random I/O speeds (both read and write) were slightly above average.

Endurance tests for all three models are still ongoing. None of the three have made it to the 2,000 read/write cycle mark. Sample #1 is currently expected to get there sometime in March 2025, while samples #2 and #3 are expected to get there sometime in April 2025.

June 8, 2024

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