Hello, I tried to set up new era device and found the following issue: kernel panics if I don't write anything to the era device after initial creation. # lvs -o lv_name,vg_name,attr,size LV VG Attr LSize data vg -wi-a----- 64.00g meta vg -wi-a----- 64.00m # blockdev --getsize /dev/vg/data 134217728 # dd if=/dev/zero of=/dev/vg/meta bs=1M count=64 oflag=direct 64+0 records in 64+0 records out 67108864 bytes (67 MB) copied, 0.0468122 s, 1.4 GB/s # dmsetup create era --table '0 134217728 era /dev/vg/meta /dev/vg/data 128' # dmsetup remove era # dmsetup create era --table '0 134217728 era /dev/vg/meta /dev/vg/data 128' << crash >> after rebooting: # era_check /dev/vg/meta examining superblock missing eras from writeset tree value size mismatch: expected 12, but got 8. This is not the btree you are looking for. era_check: /usr/include/boost/optional/optional.hpp:630: boost::optional<T>::reference_const_type boost::optional<T>::get() const [with T = unsigned int; boost::optional<T>::reference_const_type = const unsigned int&]: Assertion `this->is_initialized()' failed. Aborted (core dumped) After manual investigating superblock (using struct from drivers/md/dm-era-target.c), I found that the roots of the current_writeset and writeset_tree points to the same block number: checksum: 0xA06B0358 flags: 0x00000000 blocknr: 0 uuid: 00000000000000000000000000000000 magic: 2126579579 version: 1 data block size: 128 sectors metadata block size: 8 sectors total data blocks: 262144 current era: 2 current writeset/total bits: 262144 current writeset/root: 1 writeset tree root: 1 era array root: 9 metadata snapshot: 0 Simple workaround is to write something to /dev/mapper/era after initial creation. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
