Hello! I need to connect two MicroSD cards to a development board, and both must work with RAID 1 as A and B, but I have been reading that using RAID 1 on MicroSD is not a good practice due to limitations. How can I use RAID 1 on my MicroSD cards while avoiding the limitations that it presents?

Thank you!

 

Can you tell us what the limitations are, so we don't have to dig out the information for ourselves.

 

sure!,

Using MicroSD cards in RAID 1 has several practical limitations, mainly because they are not designed for that kind of workload. Some key issues are:

1. Wear leveling mismatch – Each MicroSD handles flash wear leveling internally and differently, so even "identical" cards will wear unevenly over time, possibly leading to silent data corruption.
2. No power-loss protection – MicroSD cards lack capacitors or safeguards against sudden power loss. A write interrupted by a power failure can corrupt the filesystem or cause inconsistent mirroring.
3. No TRIM support – Unlike SSDs, most MicroSD cards don’t support TRIM, which RAID 1 setups often rely on to manage deleted blocks efficiently.
4. Unpredictable write behavior – MicroSDs often buffer and delay writes internally. In RAID 1, this can cause data divergence between the two cards.
5. Limited write endurance – They're rated for relatively few write cycles, so RAID mirroring (which doubles the writes) accelerates wear.

 

Don't even try. Use a proper MicroSD card designed for hard duty and have usable backups. Good stable power is also a important factor in reliability.

I use Sandisk edge and Industrial cards for my projects.
https://shop.sandisk.com/products/m...ards/commercial-edge-microsd?sku=SDSDQAB-008G
https://shop.sandisk.com/products/memory-cards/microsd-cards/industrial-microsd?sku=SDSDQAF3-008G-I

Applications and Workloads

• Home Surveillance Cameras
• Transportation
• Drones
• Dashboard Cameras
• Action Cameras
• Networking
• Digital Signage
• Servers

Software RAID has always been a crap-shoot and always will be.

 

Power loss protection is also a problem for rotating drives. The solution there is a UPS. Since you don't have the problem of supporting motors at voltages higher than logic level; the demands on such a UPS should be less stringent.
Items 4 & 5 are a function of the SD cards you propose to use as mentioned by @nsaspook
In order to have the TRIM functionality you will have to implement that yourself. This is doable but may be a pain in the neck to implement and debug to the level of confidence you require. Alternatively, you could always write to unused space and have a background task to erase deleted blocks and add them to a list of unused space to delay their reuse. I'm not familiar enough with wear leveling algorithms to give any advice on these especially if identical devices may tend to behave differently.

 

Power loss protection is also a problem for rotating drives. The solution there is a UPS. Since you don't have the problem of supporting motors at voltages higher than logic level; the demands on such a UPS should be less stringent.
Items 4 & 5 are a function of the SD cards you propose to use as mentioned by @nsaspook
In order to have the TRIM functionality you will have to implement that yourself. This is doable but may be a pain in the neck to implement and debug to the level of confidence you require. Alternatively, you could always write to unused space and have a background task to erase deleted blocks and add them to a list of unused space to delay their reuse. I'm not familiar enough with wear leveling algorithms to give any advice on these especially if identical devices may tend to behave differently.

That's why my servers have hardware RAID with batteries for the data ECC cache with dual redundant power supplies. One on UPS and the other on the solar energy battery bank off-grid AC. I also have offline backup.

 

That's why my servers have hardware RAID with batteries for the data ECC cache with dual redundant power supplies. One on UPS and the other on the solar energy battery bank off-grid AC. I also have offline backup.

Did you formerly work for the Department of Redundancy Department?

 

Did you formerly work for the Department of Redundancy Department?

I think he worked for the ASB. The "Aluminum Suitcase Boys".

 

I think he worked for the ASB. The "Aluminum Suitcase Boys".

Mine was Samsonite.

 

Mine was Samsonite.
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I see you were out of uniform that day.

 

I see you were out of uniform that day.

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It was a Passport photo. They need to see your eyes and Black is hot in the tropics.

 

Black is hot in the tropics.

That's what the girls said.