Sandisk is currently the best brand for microSD cards with built in reliability and sales at a level where the best models are discounted significantly. Here are my tests of the latest Extreme Pro microSDXC A2 V30 UHS-I U3 card in the 128 GB capacity. The package is labelled SDSQXCD-128G-GN6MA.
Who?
Who wants microSD cards? Anyone with an good smartphone has a slot for storage expansion using a microSD card. Everyone with a Raspberry Pi computer has the option of running from a space saving microSD card instead of a big expensive SSD.
The Sandisk Extreme Pro provides extra reliability for those of us who work in hot climates, who work without aircon, or out in the sun down at the beach.
Who wants A2 speed? A2 means fast small random reads and writes, ideal for booting a Raspberry Pi computer.
128 GB is more than what you need to browse the Web. 128 GB is what you need when you start to save pages. download files, and take lots of photos. You photos. The new higher resolution cameras need more space for each image.
When?
Look at your current microSD card usage. 16 GB? I see people start computing projects with a 16 GB card then immediately have to upgrade to 32 GB. A few months later, they need 64 GB. A jump to 128 GB would let them use the same card for a year or two.
Last year, 64 GB was the sweet spot for low sale prices on microSD cards. This year it is 128 GB and the other day I spotted the first deep discount a good quality 256 GB card. 2025 should see lots of quality 128 GB cards at 64 GB prices.
Where?
Using a computer or smartphone or other microSD based device outside of a protected airconditioned office? Invest in a tougher microSD card. The Sandisk Extreme or Exteme Pro.
On the road or only have time for the occasional cleanup or upgrade? Buy 128 GB instead of 64 or 32. Defer all that spring cleaning until after your current projects, until you are back in the city or your office or home.
Taking pictures at an exciting location? Go wild. Capture everything from every angle. Buy the biggest card and leave the culling for your return to boring suburbia.
Why?
Flash memory storage options usually have a range of capacities and the smallest capacity is almost always slower. The Sandisk Extreme Pro range currently starts with the slower 32 GB size and gets up to full speed at 64 GB. 128 GB also has extra spare space for the card to perform background erases to maintain better write speeds. Buying bigger than you need is always good in flash memory.
The Linux operating system can install in a 4 GB card. 16 GB gives the OS the margin to do anything. It is applications needing more. I set up a lot of desktop computers with 64 GB and 128 GB SSDs back in the past. 64 GB worked but modern Web browsers and similar applications push you up to 128 GB. Start with 128 GB to avoid an upgrade a few months later.
Photographers will find they need more like 512 GB. People making videos will need TeraBytes. Whatever you decide first time around, you probably need double. Currently there are deals on good cards in the 128 GB capacity and the small cost difference makes 128 GB the minimum for a desktop style computer.
For people using a Pi 4 with huge magnetic disk plugged into the USB 3 port, the extra space in the 128 GB boot microSD card lets you perform actions like compression and video format conversion prior to archiving to the magnetic disk. This 128 GB card is fast enough for a file server archiving function.
Several parallel media format conversions or encryptions or similar would better fit a USB SSD. Multiple media format conversions in parallel would better fit an NVMe SSD in a Pi model 5.
microSD cards wear out faster than full scale SSDs. Buying the best models will give you an extra margin of safety. The Sandisk Extreme Pro provides extra protection and is sometimes on sale at a price similar price to the Sandisk Extreme, a reason to grab the Extreme Pro.
Buying double or more in capacity spreads out the workload to reduce wear and increase life. The Sandisk Extreme Pro 128 GB was on sale at a price near the 64 GB,another reason to buy bigger.
If you are not in a rush to buy today, watch the next models up in quality and speed and capacity then grab the best of the biggest for the longest term benefit.
Way?
In the speed tests below, the Sandisk Extreme Pro gives you spare speed to do more than you would normally do with a microSD card. Think about placing all your travel photographs in your smartphone for display the next time you share coffee with your friends. Copying a hundred gigabytes to the microSD card in your phone is normally painfully slow. The Sandisk Extreme Pro cuts the copy time in half or down to one third. You get the option to copy everything in one big hit instead of wasting time selecting bits here and bits there.
My smartphone now runs faster after an upgrade to a later model microSD card. Finding photos is noticeably faster to the point where I have to slow down scrolling from the new supersonic maximum speed.
For a Raspberry Pi 5, this microSD card gives you the maximum speed to run lots of projects from the microSD card instead of plugging in a USB disk. You may defer the expense of an NVMe SSD for months or longer.
The Pi 4 can run at maximum microSD card speed continuously without this card slowing down. If the Pi 4 microSD card is not fast enough, you can move the microSD card to a good quality USB adaptor for double the speed.
You can use the Pi 4 style USB adaptor approach to make a Pi Zero 2 run faster although this Sandisk Extreme Pro is faster than what a Zero 2 can use. You might use the Extreme Pro to replace an existing Extreme in a Pi 4 then move the Extreme to the Zero 2. The move will upgrade both machines.
Worth?
Imagine you once a year trip. A safari in Africa. The rare sighting of a lioness with cubs. Aah! The memory card is full.
Buying two or four times the storage capacity you need will avoid one of the most common technology disruptions, lack of space. In the case of a camera/smartphone with microSD, buying 128 GB instead of 64 is good practice. The same with cameras using SD cards then a download to the microSD card in your Raspberry Pi 400 computer. With more space in the computer, you can clear out the card in your camera more often.
Although for a week long safari in Africa, you will need much more space. What you might use is a 128 GB card per day. Spot a sale with a big discount and buy one card for every day of your trip. Start every day with heaps of space.
MicroSD cards are also the smallest and lightest form of storage when travelling. You could easily fir two cards per day. Replicate the full day of photographs to a second bag, one set in your suitcase and another set in your wallet to survive baggage handlers. When I shopped last week, 128 GB cards were the best discounted and produced the lowest cost per GB of storage.
What?
Card information from Linux:
Name: SR128
Date: 11/2024
OEM ID: 0x5344
The package contains an SD adaptor. The package says the product is SDSQXCD-128G-GN6MA and that may be for the combination of the card plus adaptor. The back of the card has an id imprinted: 4466XC061556
Raspberry Pi Zero 2
The Pi Zero 2 has the slowest microSD slot among the 64 bit models of Raspberry Pi SBCs, Single Board Computers. The USB 2 socket can be faster with modern cards. Given the single USB socket on the Zero 2, you need a hub for a keyboard, mouse, and USB boot device. I use a Raspberry Pi official keyboard with built in USB 2 hub for the mouse and the USB boot device.
Pi Zero 2 microSD card slot:
Sequential write speed 18754 KB/sec (target 10000) – PASS
Random write speed 763 IOPS (target 500) – PASS
Random read speed 1943 IOPS (target 1500) - PASS
Pi Zero 2 booted from Sandisk USB 3.0 microSD card adaptor:
Sequential write speed 34102 KB/sec (target 10000) – PASS
Random write speed 931 IOPS (target 500) – PASS
Random read speed 1594 IOPS (target 1500) - PASS
Pi Zero 2 booted from a generic USB 3.0 microSD card adaptor:
Sequential write speed 37321 KB/sec (target 10000) – PASS
Random write speed 929 IOPS (target 500) – PASS
Random read speed 1649 IOPS (target 1500) - PASS
Raspberry Pi 4
Pi 4 microSD card slot:
Sequential write speed 39313 KB/sec (target 10000) – PASS
Random write speed 835 IOPS (target 500) – PASS
Random read speed 2300 IOPS (target 1500) – PASS
Pi 4 booted from generic USB 3.0 adaptor in USB 3 port:
Sequential write speed 86573 KB/sec (target 10000) – PASS
Random write speed 804 IOPS (target 500) – PASS
Random read speed 1946 IOPS (target 1500) - PASS
Pi 4 booted from generic USB 3.0 adaptor in USB 2 port:
Sequential write speed 32283 KB/sec (target 10000) – PASS
Random write speed 944 IOPS (target 500) – PASS
Random read speed 1674 IOPS (target 1500) - PASS
Raspberry Pi 5
Pi 5 microSD card slot:
Sequential write speed 74684 KB/sec (target 10000) – PASS
Random write speed 3108 IOPS (target 500) – PASS
Random read speed 6097 IOPS (target 1500) - PASS
Raspberry Pi 5 booted from Kingston Mobilite G4 USB 3 adaptor:
Sequential write speed 87938 KB/sec (target 10000) – PASS
Random write speed 1087 IOPS (target 500) – PASS
Random read speed 2009 IOPS (target 1500) – PASS
Raspberry Pi 5 booted from Sandisk USB 3 adaptor:
Sequential write speed 100592 KB/sec (target 10000) – PASS
Random write speed 976 IOPS (target 500) – PASS
Random read speed 1967 IOPS (target 1500) - PASS
Kingston Mobilite G4 USB 3 Type A adaptor
Benchmark in fast computer with USB 3.1 Gen 2 (10 Gbps) port.
Average read rate 1000 MB 100 times: 95.4 MBps
Average write rate 1000 MB 100 times: 88.0 MBps
Average access time 0.70 msec
Ugreen USB 3 Type C adaptor
Benchmark in fast computer with USB 4 (40 Gbps) port.
Average read rate 1000 MB 100 times: 89.8 MBps
Average write rate 1000 MB 100 times: 85.0 MBps
Average access time 0.57 msec
Sandisk MobileMate USB 3.0 adaptor SDDR-B531
Benchmark in fast computer with USB 3.1 Gen 2 (10 Gbps) port. Sandisk advertise that their cards can exceed the UHS-I speed, 104 MBps, in the right circumstances and this adaptor makes that extra speed possible in Intel based computers.
Average read rate 1000 MB 10 times: 176.0 MBps
Average write rate 1000 MB 10 times: 102.5 MBps
Average access time 0.49 msec
When writing an image file to disk, the speed was only 93 MBps. The Sandisk magic speed does not work all the time.
White USB 3.0 Card Reader
Benchmark in fast computer with USB 3.1 Gen 2 (10 Gbps) port.
Average read rate 1000 MB 100 times: 95.9 MBps
Average write rate 1000 MB 100 times: 88.8 MBps
Average access time 0.52 msec
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