I updated my backup server this weekend from CentOS 7 to CentOS 8. OS disk is SSD, /dev/md0 are two 4TB WD mechanical drives. No hardware was changed. 1. wiped all drives 2. installed new copy of 8 on system SSD 3. re-created the 4TB mirror /dev/md0 with the same WD mechanical drives 4. created the largest single partition possible on /dev/md0 and formatted it ext4 5. waited several hours for the creation of /dev/md0 to finish 6. copied all data back onto /dev/md0 Both installs were a full workstation, with Gnome. The mirror is mounted via fstab as: /dev/md0 /mnt/raid1 ext4 defaults 0 0 Under CentOS 7 the /dev/md0 mirror was silent when not in use. Now under 8, the hard drives are constantly "pinged" by some process, at about the same frequency as a heartbeat monitor. I can not figure out what process is keeping them active. iotop does show a process named [ext4lazyinput]. Is there something I've missed?