We can simulate this using USB device and momentary remove power. Kernel recognized this as joining new properly operatings device. we tell to kernel that we completly disconnect device and connect to it again. Usually only this is allways possible and we allways forced to.Īt points 1.
Unfortunately usually damaged device keeps rootfs, or driver keeps both damaged device and device that keeps rootfs
Unusable ansvers, really qualified as spam from people who wants to help, but doesn't understand about problem nature: Witiout this, kernel serve device as read-only, like 'CD-ROM', and no other command has chance to works properly, including mount/remount -o read-write, fsck and others.
How to manually tell to kernel, hdd block device operates normally? This is kernel functionality maked for damage prevention, but it is useable only at 1. Maybe lost/timeouted FC packetĪt this situations device is really read-write, but linux kernel marks this device internally as read-only and is used as read-only. Momentary lost connection over FC or FCoE.FC cable or SAN device (array disks over Fibre Channel) is overloaded.Host machine is overloaded, then linux guest virtual HDD writings are timeouted.Returned writing problems are depended on HDD condition In my experience this occurs in situations: Mount: cannot remount block device /dev/sda1 read-write, is write-protectedīecause WHOLE device sda keeping rootfs sda1 is READONLY. There are many other errors, like "lost write page", "Journal has aborted", "Buffer I/O error", "hard resetting link" and many others.Īfter this, remount cause: mount / -o remount,rw ata3.00: failed command: WRITE FPDMA QUEUED ata3.00: exception Emask 0x0 SAct 0x11fff SErr 0x0 action 0圆 frozen ata3.00: exception Emask 0x0 SAct 0x1 SErr 0x0 action 0圆 frozen ata3.00: device reported invalid CHS sector 0 ata3: SATA link up 3.0 Gbps (SStatus 123 SControl 300) ata3.00: failed command: READ FPDMA QUEUED After this any writings to any partition / filesystem located on this device cause switch it as readonly together with device state, because any writings are impossible.Įxample from dmesg, this is simulation for guest linux on windows8 using VirtualBox when defrag takes guests device image: ata3.00: exception Emask 0x0 SAct 0x1 SErr 0x0 action 0圆 frozen
Usually after some problems with readings or writings to block device, kernel decides to switch flag for WHOLE DEVICE as read-only.