root@NAS2:/# mount
/dev/md0 on / type ext4 (rw,relatime,journal_checksum,barrier,data=ordered)
none on /dev type devtmpfs (rw,nosuid,noexec,relatime,size=501960k,nr_inodes=125490,mode=755)
none on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000)
none on /proc type proc (rw,nosuid,nodev,noexec,relatime)
none on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)
/tmp on /tmp type tmpfs (rw,relatime)
/run on /run type tmpfs (rw,nosuid,nodev,relatime,mode=755)
/dev/shm on /dev/shm type tmpfs (rw,nosuid,nodev,relatime)
none on /sys/fs/cgroup type tmpfs (rw,relatime,size=4k,mode=755)
cgmfs on /run/cgmanager/fs type tmpfs (rw,relatime,size=100k,mode=755)
cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,relatime,cpuset,release_agent=/run/cgmanager/agents/cgm-release-agent.cpuset,clone_children)
cgroup on /sys/fs/cgroup/cpu type cgroup (rw,relatime,cpu,release_agent=/run/cgmanager/agents/cgm-release-agent.cpu)
cgroup on /sys/fs/cgroup/cpuacct type cgroup (rw,relatime,cpuacct,release_agent=/run/cgmanager/agents/cgm-release-agent.cpuacct)
cgroup on /sys/fs/cgroup/memory type cgroup (rw,relatime,memory,release_agent=/run/cgmanager/agents/cgm-release-agent.memory)
cgroup on /sys/fs/cgroup/devices type cgroup (rw,relatime,devices,release_agent=/run/cgmanager/agents/cgm-release-agent.devices)
cgroup on /sys/fs/cgroup/freezer type cgroup (rw,relatime,freezer,release_agent=/run/cgmanager/agents/cgm-release-agent.freezer)
cgroup on /sys/fs/cgroup/blkio type cgroup (rw,relatime,blkio,release_agent=/run/cgmanager/agents/cgm-release-agent.blkio)
none on /proc/bus/usb type devtmpfs (rw,nosuid,noexec,relatime,size=501960k,nr_inodes=125490,mode=755)
none on /sys/kernel/debug type debugfs (rw,relatime)
securityfs on /sys/kernel/security type securityfs (rw,relatime)
/dev/md2 on /volume1 type ext4 (rw,relatime,journal_checksum,synoacl,stripe=32,data=writeback,jqfmt=vfsv0,usrjquota=aquota.user,grpjquota=aquota.group)
none on /config type configfs (rw,relatime)
root@NAS2:/# mdadm --assemble --force /dev/md20 /dev/sdb5
mdadm: cannot open device /dev/sdb5: Device or resource busy
mdadm: /dev/sdb5 has no superblock - assembly aborted
root@NAS2:/#
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