On new db create discovery rule vfs.fs.discovery and one item prototype. Items are successfully discovered, but discovery rule got error "cannot create item [vfs.fs.size[/,pfree]]: item already exists".

Server log in attachment, created for server from branch ZBXNEXT-1058, but it should not matter much.

mount and /proc/mounts outputs:

• mount
  /dev/sda1 on / type ext3 (rw,errors=remount-ro)
  proc on /proc type proc (rw)
  none on /sys type sysfs (rw,noexec,nosuid,nodev)
  none on /sys/fs/fuse/connections type fusectl (rw)
  none on /sys/kernel/debug type debugfs (rw)
  none on /sys/kernel/security type securityfs (rw)
  none on /dev type devtmpfs (rw,mode=0755)
  none on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
  none on /dev/shm type tmpfs (rw,nosuid,nodev)
  none on /var/run type tmpfs (rw,nosuid,mode=0755)
  none on /var/lock type tmpfs (rw,noexec,nosuid,nodev)
  none on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
  /dev/sda3 on /data type ext3 (rw)
  rpc_pipefs on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
  nfsd on /proc/fs/nfsd type nfsd (rw)

• cat /proc/mounts
  rootfs / rootfs rw 0 0
  none /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0
  none /proc proc rw,nosuid,nodev,noexec,relatime 0 0
  none /dev devtmpfs rw,relatime,size=2022148k,nr_inodes=505537,mode=755 0 0
  none /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
  /dev/disk/by-uuid/58114a9f-7bf2-413f-a4b9-55ed30c10616 / ext3 rw,relatime,errors=remount-ro,data=ordered 0 0
  none /sys/fs/fuse/connections fusectl rw,relatime 0 0
  none /sys/kernel/debug debugfs rw,relatime 0 0
  none /sys/kernel/security securityfs rw,relatime 0 0
  none /dev/shm tmpfs rw,nosuid,nodev,relatime 0 0
  none /var/run tmpfs rw,nosuid,relatime,mode=755 0 0
  none /var/lock tmpfs rw,nosuid,nodev,noexec,relatime 0 0
  none /lib/init/rw tmpfs rw,nosuid,relatime,mode=755 0 0
  /dev/sda3 /data ext3 rw,relatime,errors=continue,data=ordered 0 0
  rpc_pipefs /var/lib/nfs/rpc_pipefs rpc_pipefs rw,relatime 0 0
  nfsd /proc/fs/nfsd nfsd rw,relatime 0 0