mount

man mount

Since Linux 2.4.0 it is possible to remount part of the file hierarchy somewhere else. The call is
      mount --bind olddir newdir
After this call the same contents is accessible in two places.  One can also remount a single file (on a single file). This call attaches only (part of) a single filesystem, not possible submounts.


The entire file hierarchy including submounts is attached a second place using
      mount --rbind olddir newdir

Note that the filesystem mount options will remain the same as those on the original mount point, and cannot be changed by passing the -o option along with --bind/--rbind.

Since Linux 2.5.1 it is possible to atomically move a mounted tree to another place. The call is
      mount --move olddir newdir

--bind: 싱글파일시스템 일부를 마운트.
--rbind: bind와 같음 다른것은 rbind는 submount도 끌고 옴.
--bind/--rbind 는 오리지날 마운트 옵션을 변경할 수 없다.
--move: mount point 이동

submount 는
lv1 /data
lv2 /data/sub 로 마운트 밑에 다시 마운트 하는 것을 말함


mount /dev/sdb1 /data
mount /dev/sdb2 /data/sub1/sub2
mount --bind /data/sub1 /data1 => data1 은 sdb1
mount --rbind /data/sub1 /data1 => data1 은 sdb2

sanique

1. dsb_mnt_counts -> failover -> snq_clm_umount -> snq_csm_umount -> dsb_mnt_count 보정?

=> dsb 보정하려면 super block 락이 필요하다.

clm_umount 했기때문에 불가능하다.

2. mount 

clm mount -> log mount -> csm mount -> dsb_mnt_counts

3. umount

dsb_mnt_counts -> log umount -> clm umount -> csm umount

dsb_mnt_counts -> csm umount -> log umount -> clm umount

4. CSM umount -> CLM umount: IO 금지

CLM umount 한 뒤로는 IO 가 불가능하다.

CSM umount 실패하면 재시도 해야한다.