Input/Output Error
Production Risk
EIO on a production disk requires immediate attention. Activate failover, back up data, and replace the drive.
A hardware-level I/O error occurred during a read or write operation. This typically indicates physical disk failure, bad sectors, or a failing storage device. Data integrity cannot be guaranteed after this error.
- 1The storage device has bad sectors that cannot be read or written.
- 2The disk is physically failing or the SATA/NVMe cable is loose.
- 3A USB drive was unplugged while a write was in progress.
- 4Filesystem corruption caused the kernel to reject an I/O operation.
Reading from a disk with failing sectors.
$ dd if=/dev/sda of=/dev/null bs=512 dd: error reading '/dev/sda': Input/output error
expected output
dd: error reading '/dev/sda': Input/output error $ dmesg | tail [ 1234.567] Buffer I/O error on dev sda, logical block 0
Fix
Check disk health and run filesystem repair
WHEN When EIO appears on a mounted filesystem
# Check SMART status sudo smartctl -a /dev/sda # After unmounting, run filesystem check sudo umount /dev/sda1 sudo fsck -f /dev/sda1
Why this works
smartctl reports disk health metrics that indicate whether the drive is failing. fsck repairs filesystem inconsistencies caused by I/O errors.
✕ Continue writing to a disk reporting EIO errors
I/O errors indicate physical media problems. Continued writes may accelerate data loss. Back up immediately.
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