admin-guide/device-mapper/log-writes.rst

5 This target takes 2 devices, one to pass all IO to normally, and one to log all
22 This works by attaching all WRITE requests to a list once the write completes.
24 the FLUSH request completes we log all of the WRITEs and then the FLUSH.  Only
43 have all the DISCARD requests, and then the WRITE requests and then the FLUSH
62    dev_path	 Device that all of the IO will go to normally.
85 	  mkfs.btrfs -f /dev/mapper/log
107   TABLE="0 $(blockdev --getsz /dev/sdb) log-writes /dev/sdb /dev/sdc"
109   mkfs.btrfs -f /dev/mapper/log
112   mount /dev/mapper/log /mnt/btrfs-test
119   replay-log --log /dev/sdc --replay /dev/sdb --end-mark fsync
120   mount /dev/sdb /mnt/btrfs-test
127   TABLE="0 $(blockdev --getsz /dev/sdb) log-writes /dev/sdb /dev/sdc"
129   mkfs.btrfs -f /dev/mapper/log
132   mount /dev/mapper/log /mnt/btrfs-test
138   replay-log --log /dev/sdc --replay /dev/sdb --end-mark mkfs
139   btrfsck /dev/sdb
140   replay-log --log /dev/sdc --replay /dev/sdb --start-mark mkfs \
141 	--fsck "btrfsck /dev/sdb" --check fua