1、SD card and TF card
SD Card: Also known as a standard SD card, it has a size of 32 x 24 x 2.1 mm and is generally used in devices such as digital cameras, sound cards and capture cards.
TF card: also called micro SD card, its size is 15 x 11 x 1 mm, generally used in cell phones, game consoles, drones and car recorders and other devices; because of its more compact size, and can also be converted to SD card through the SD card holder, so TF card is more popular and common in daily use.
2、Card face common signs
2.1. Capacity classification marking
| Capacity classification marking | capacity range | file system |
|---|---|---|
| SD | Not more than 2 GB | FAT16 |
| SDHC | Greater than 2 GB, but not greater than 32 GB | FAT32 |
| SDXC | Greater than 32 GB, but not greater than 2 TB | exFAT |
| SDUC | Greater than 2 TB but not greater than 128 TB | exFAT |
This capacity classification is of little reference value because the card face usually has a specific numerical capacity designation; the current capacity classification designation for common SD cards is SDXC.
Note: The exFAT file system is optimized for flash memory and is suitable for USB flash drives and SD cards larger than 32GB; it has the advantage of having a single file size of up to 16EB.
The FAT32 file system is generally used for USB flash drives and SD cards up to 32GB; its disadvantage is that the maximum size of a single file cannot exceed 4GB.
The NTFS file system is typically used on hard disks with single file sizes up to 256TB.
2.2. Bus interface identification
| BUS interface identification | Bus Interface Type | Bus speed | Capacity classification marking |
|---|---|---|---|
| - | High Speed | 25MB/s | SD、SDHC、SDXC |
| Ⅰ | UHS-I | 104MB/s | SDHC、SDXC |
| Ⅱ | UHS-II | 312MB/s | SDHC、SDXC |
| Ⅲ | UHS-III | 624MB/s | SDHC、SDXC |
Tip: The UHS-I bus is currently common, UHS-II is rare, and UHS-III is almost non-existent.
While SD cards with UHS-II or UHS-III buses can be used in UHS-I-only devices, they don't take advantage of their speed and the extra money spent is wasted.
2.3. Minimum sequential write speed marking
| Minimum sequential write speed | Speed class marking | UHS Speed Class Marking | Video speed grade marking |
|---|---|---|---|
| 90MB/s | V90 | ||
| 60MB/s | V60 | ||
| 30MB/s | U3 | V30 | |
| 10MB/s | C10 | U1 | V10 |
| 6MB/s | C6 | V6 | |
| 4MB/s | C4 | ||
| 2MB/s | C2 |
C10 = U1 = V10 : Can be used to record Full HD (1080P) video.
U3 = V30: Can be used to record 2k or 4k video.
V60: Can be used to record 4k video.
V90: Can be used to record 8k video.
Tip: Because SD card will heat up and lose speed when working for a long time, the "Minimum Sequential Write Speed" is more valuable than the "Maximum Sequential Write Speed".
2.4. Random read/write performance level identification
| Performance Level Marking | random access (memory) | random access |
|---|---|---|
| A2 | 4000 IOPS | 2000 IOPS |
| A1 | 1500 IOPS | 500 IOPS |
Tip: Higher IOPS values are better when reading and writing large numbers of small files.
2.5. Brand identity
| brand identity | brand name | brand awareness | Well-known models / Warranty period | Price / Capacity |
|---|---|---|---|---|
| Kingston | Kingston (name) | top brand | CANVAS Go Plus / Lifetime | 50 / 64 GB |
| SAMSUNG | the belt of Orion | top brand | EVO Plus / 10 years | 50 / 128 GB |
| QL | made in Kyoto and Tokyo | second-tier brand | Kirin Series / 10 years | 50 / 128 GB |
| SanDisk | SanDisk | top brand | Extreme / Lifetime (valid in product packaging) | 60 RMB / 64 GB |
| KIOXIA | armor warrior | top brand | EXCERIA G2 / 5 years | 30$ / 64 GB |
| Lexar | Rexha | top brand | 633X / 10 years | 30$ / 64 GB |
| HIKSEMI | Haikang (company name) | second-tier brand | The Birdie / 7 years (product packaging remains valid) | 30$ / 64 GB |
| Netac | Lanco (brand) | second-tier brand | 667X (Ultra Supreme Pro) / 10 Years | 20$ / 64 GB |
| aigo | MIM-104 Patriot surface-to-air missile | second-tier brand | T1 (High Speed Pro) / 3 years | 20$ / 64 GB |
| BANQ | Banq | second-tier brand | For Surveillance / 1 year | 20$ / 64 GB |
| EAGET | MemoryJet | second-tier brand | For Surveillance / 1 year | 20$ / 64 GB |
According to the review by DIYLAB, the UP owner of B station, Kingston CANVAS Go Plus has the best overall performance, the disadvantage is that it is a bit expensive.
Next, the Samsung EVO Plus and the Kyoto-created Kirin series, also perform well and offer better value for money.
According to the reviewers' comments, Kingston CANVAS Go Plus is a worthy card king, Kyuzo Kirin 256G will perform better, and Armor Man G2 is a good card for civilians with very few damage cases.
Note: Warranty means the SD card can be repaired or exchanged for a new one, it does not include data recovery, so it is better to have multiple ways of backing up important data.
3、SD card life
| Flash Particle Type | bits per unit | Number of times erasable | retrieve time | Programming time | Erase Time |
|---|---|---|---|---|---|
| SLC particles | 1 | 100000 | 25us | 300us | 1500us |
| MLC particles | 2 | 5000 | 50us | 600us | 3000us |
| TLC particles | 3 | 1000 | 75us | 900us | 4500us |
The lifespan of an SD card is not measured in years, but in the number of times it can be erased or written (P/E), with SLC > MLC > TLC > QLC.
SLC is generally used as a cache, MLC is used for enterprise products, TLC is mostly used for consumer products, and QLC is used for low-end products.
As a result, SD cards are not suitable for storing files that require high-frequency reading and writing, so cards used for surveillance generally have a very short lifespan (cards optimized for surveillance generally have the Endurance logo), and cell phone manufacturers do not support the installation of applications on micro SD cards.
When the SD card reaches its write limit, the card is usually automatically write-protected (read only, not write), and you need to back up your data as soon as possible.
Note: The life of an SD card is related to the storage capacity density in addition to the number of times the flash memory particles can be erased or written;
For example, 512GB of MLC has a guaranteed write life of 600TBW, but 2TB of TLC has a guaranteed write life of 1200TBW.
4. Other considerations
-
Because read speeds are generally faster than write speeds, the speeds advertised by vendors are generally sequential read speeds, so pay extra attention to (sequential) write speeds.
-
The stability and compatibility of the SD card is generally more important than the read/write speed, and the factors affecting compatibility and stability are generally: the main control chip and flash memory particles.
-
With a brand like Samsung, the master control and particles can be produced in-house, so quality and compatibility will be more assured.
-
It's best to choose a brand that produces both memory cards, USB flash drives and SSDs.
-
If the SD card is used in harsh working environments such as high temperature, low temperature, dust, deep water, etc., the SD card's attributes such as waterproof, anti-shock, anti-magnetic, anti-radiation, drop-proof, resistance to heat and cold, and resistance to abrasion, etc., should also be considered.
this paper references
【1】【Hardware Tea Talk】【How to choose a memory card?What are the differences between SD, TF and CFe cards? [bilibili] [2024-01-04]
【2】【DIYLAB】【The latest and most comprehensive performance-grade TF card comparison review】【bilibili】【2023-11-17
[3] [Yongjiang Moyun] [The relationship between memory cards, USB flash drives and solid state drives] [bilibili] [2024-03-01
[4] [The Eight Reveries Chronicles] [SD card iteration and performance notes and tests] [bilibili] [2023-07-31
[5] [Winnie's Own Place] [Why hasn't the TF card replaced the SD card? [Knowing][2022-11-22]
[6] [Easy My Hard Disk Data Recovery] [TF card, SD card, USB flash drive, ssd, what are these three types of storage media and how does the life expectancy compare? [Knowledge] [2023-08-10]