Application Note: eMMC Lifetime Optimization

Introduction

Embedded systems often rely on eMMC flash storage as their primary non-volatile memory.
Unlike traditional hard drives, eMMC has a limited endurance, measured in Program–Erase (P/E) cycles — typically around 3,000 cycles for standard-grade parts.

Each P/E cycle represents a complete write–erase–rewrite operation to the same memory cell.
As these cycles accumulate, flash memory cells wear out, which can lead to performance degradation, data corruption, or system instability.

Therefore, optimizing the usage of eMMC is essential for extending product lifetime, improving reliability, and minimizing field failures — especially in industrial or IoT environments where continuous operation is expected.

This document outlines both software-level and hardware-level best practices to maximize eMMC endurance for SolidRun-based platforms such as i.MX6, i.MX8M, and RZ series systems.

1. Software-Level Optimization

1.1 Use tmpfs for Temporary Files

tmpfs stores temporary files in RAM rather than on the eMMC, reducing write cycles.
Mounting common temporary directories as tmpfs is one of the simplest and most effective optimizations.

Add the following entries to /etc/fstab:

This ensures temporary files are stored in memory and cleared on reboot.

1.2 Reduce or Disable Logging (Legacy Systems)

Frequent writes from log files can significantly reduce eMMC lifespan.
If persistent logs are not strictly required, disable or redirect them to volatile storage.

To disable system logging (syslog):

To store logs in RAM:

To prevent recording read access times:
Modify the root filesystem entry in /etc/fstab to include noatime:

1.3 Disable or Minimize Swap Usage

Swap operations involve heavy read/write access and can wear out flash memory rapidly.
It is highly recommended to disable swap or reduce its usage.

To temporarily reduce swap activity:

To disable swap completely:

To make this change permanent:
Add the following line to /etc/sysctl.conf:

1.4 Use SquashFS for Read-Only Files

SquashFS is a compressed, read-only filesystem ideal for static system files.
It reduces writes, improves boot speed, and saves space.

Example:

Use SquashFS for the root filesystem or firmware images that rarely change.

1.5 Use OverlayFS for Writable Layers

For systems that require both a read-only root filesystem and temporary writable areas,
OverlayFS can be used to redirect all write operations to RAM.

Example entry in /etc/fstab:

This ensures the base system remains untouched, while volatile changes are stored in temporary memory.

2. Hardware and System-Level Recommendations

2.1 Use Industrial-Grade eMMC

For production or industrial deployments, always select industrial-grade eMMC.
They offer:

• Up to 10× endurance (typically 30,000 P/E cycles)

• Wider temperature range (−40°C to +85°C or more)

• Enhanced wear leveling and ECC

• Power-loss protection features

Manufacturers such as Micron, Swissbit, Kingston, and Western Digital provide industrial-grade variants suitable for SolidRun platforms.

2.2 Monitor eMMC Health

Modern eMMC devices (v5.0+) provide lifetime estimation through the EXT_CSD register.
Regular monitoring helps detect early wear and schedule proactive replacements.

Example command:

Interpretation:

• 0–4 → Healthy

• 5–10 → Approaching end-of-life

Integrating this check into maintenance scripts helps predict and prevent failures.

2.3 Avoid Write-Heavy Applications on eMMC

Databases, cache directories, and frequent log writes can shorten eMMC lifespan.
Recommended practices:

• Move databases (e.g., SQLite, PostgreSQL) to RAM disks, external SSDs, or network storage

• Use journald volatile mode:

  sed -i 's/#Storage=auto/Storage=volatile/' /etc/systemd/journald.conf systemctl restart systemd-journald

• Redirect application cache to /tmp or /var/tmp (mounted on tmpfs)

2.4 Use External Storage for Heavy Workloads

If the application involves frequent read/write cycles:

• Use NVMe SSDs for higher endurance and performance

• Use industrial SD cards for removable media

• Or offload data logging to networked storage (NFS, iSCSI, etc.)

3. Practical Configuration Example

Below is an example configuration for an optimized eMMC-based system:

/etc/fstab

/etc/sysctl.conf

Optional (journald volatile mode):

4. Summary

Conclusion

Optimizing eMMC usage is critical for ensuring system longevity and reliability in embedded products.
By combining both software techniques (tmpfs, noatime, OverlayFS) and hardware strategies (industrial-grade eMMC, monitoring, external storage), engineers can significantly extend the operational life of SolidRun-based platforms.

These best practices should be integrated into the image build process, factory configuration, and maintenance routines of all SolidRun embedded products.