Fixing Samsung 990 Pro SSD ext4 Filesystem Read-Only Issue

Problem Background#

If you’re experiencing ext4 filesystem suddenly becoming read-only on a Linux system with Samsung 990 Pro SSD, or seeing drive drop phenomena in system logs while hardware detection tools report no errors, you may have encountered a known Samsung SSD issue.

Typical symptoms of this problem include:

Filesystem suddenly switches to read-only mode
Unable to write any data
I/O errors may appear in system logs
Hard drive health checks with smartctl and similar tools show normal status
Particularly common with Samsung 990 Pro drives running firmware version 4B2QJXD7 or earlier versions

The issue manifests with symptoms similar to the following image (symptoms disappear after server reboot, resembling a drive drop):

Ext4 Read-Only Issue

WARNING
Before performing any operations, make sure to back up your important data! While this issue typically doesn’t cause data loss, it’s always better to be safe.

Problem Investigation#

1. Check Filesystem Status#

First, confirm whether the filesystem has actually become read-only:

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# Check mount status
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mount | grep "ro,"
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# Try creating a test file
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touch /path/to/mountpoint/test.txt

If you see a Read-only file system error, the filesystem has indeed become read-only.

2. Check System Logs#

Check system logs for more information:

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# View kernel logs
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dmesg | grep -i "error\|ext4\|nvme"
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# View system logs
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journalctl -xe | grep -i "error\|ext4\|nvme"

3. Check SSD Information#

View your SSD’s model and firmware version:

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# View NVMe device information
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sudo nvme list
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# View detailed information
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sudo nvme id-ctrl /dev/nvme0
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# Use smartctl to check
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sudo smartctl -a /dev/nvme0

If your device is a Samsung 990 Pro with firmware version 4B2QJXD7 or similar, you’ve likely encountered Samsung SSD’s power management bug.

Solutions#

This problem has two main solutions. I recommend trying Solution 2 (kernel parameter fix) first, as it’s simpler and takes effect immediately. If the problem persists, then consider updating the firmware.

Solution 1: Update SSD Firmware#

Samsung provides Samsung Magician software for Windows users, but Linux users can use Samsung’s bootable ISO images to update firmware.

Step 1: Download Firmware#

Visit Samsung’s official firmware download page:

https://semiconductor.samsung.com/consumer-storage/support/tools/

Find and download the latest firmware ISO image for your SSD model.

Step 2: Extract and Run Firmware Update Tool#

You don’t need to burn a CD or create a bootable USB drive - you can extract and run it directly on your Linux system:

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# Download the ISO image (replace with actual download link)
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curl -OL https://semiconductor.samsung.com/.../firmware.iso
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# Extract initrd
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bsdtar -xf firmware.iso initrd
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# Extract root filesystem
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bsdtar -xf initrd root
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# Run firmware update tool
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sudo ./root/fumagician/fumagician

Upgrade Firmware 1

Upgrade Firmware 2

Step 3: Reboot System#

After the firmware update completes, reboot your system for the update to take effect:

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sudo reboot

Solution 2: Kernel Parameter Fix (Recommended)#

This is a simpler and proven permanent solution. The root cause is Samsung SSD’s power management feature having compatibility issues with Linux, and disabling NVMe power state management can completely resolve the issue.

TIP
This solution has been verified effective on multiple affected systems and is the most recommended approach.

Step 1: Edit GRUB Configuration#

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sudo nano /etc/default/grub

Find the GRUB_CMDLINE_LINUX_DEFAULT line and add the following parameter inside the quotes:

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nvme_core.default_ps_max_latency_us=0

Example after modification:

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GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nvme_core.default_ps_max_latency_us=0"

Step 2: Update GRUB Configuration#

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# Debian/Ubuntu systems
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sudo update-grub
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# RHEL/CentOS/Fedora systems
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sudo grub2-mkconfig -o /boot/grub2/grub.cfg
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# Arch Linux systems
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sudo grub-mkconfig -o /boot/grub/grub.cfg

Step 3: Reboot System#

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sudo reboot

Step 4: Verify Parameter is Active#

After reboot, verify the kernel parameter has taken effect:

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cat /proc/cmdline | grep nvme_core

You should see nvme_core.default_ps_max_latency_us=0 in the output.

Root Cause#

This issue is a resurgence of an old Samsung SSD problem in Linux systems. Over the years, various Samsung SSD models (including 970 EVO, 980 Pro, etc.) have experienced similar issues.

The root cause is a compatibility issue between Samsung SSD’s Power State Management feature and the Linux kernel’s NVMe driver. When the SSD enters certain power states, it can cause I/O timeouts, which triggers the filesystem’s protection mechanism to switch the filesystem to read-only mode to prevent data corruption.

By setting nvme_core.default_ps_max_latency_us=0, we disable the NVMe device’s Automatic Power State Transition (APST), forcing the SSD to remain in a high-performance state, thus avoiding this issue.

Fixing Samsung 990 Pro SSD ext4 Filesystem Read-Only Issue

Problem Background#

Problem Investigation#

1. Check Filesystem Status#

2. Check System Logs#

3. Check SSD Information#

Solutions#

Solution 1: Update SSD Firmware#

Step 1: Download Firmware#

Step 2: Extract and Run Firmware Update Tool#

Step 3: Reboot System#

Solution 2: Kernel Parameter Fix (Recommended)#

Step 1: Edit GRUB Configuration#

Step 2: Update GRUB Configuration#

Step 3: Reboot System#

Step 4: Verify Parameter is Active#

Root Cause#

References#