I have a 1TB usb disk, I used GParted to divide it into 3 partition, sdb1 is primary 50G, file system is ext4, sdb5 is logical 450G, file system is ext3, sdb6 is logical 500G, file system is ext3, after that, I made a dir in /media, then I input: "mount -o rw /dev/sdb1 /media/p1/"

I accessed into the p1, and input "mkdir 123", but i got a message "mkdir: can't create directory 123, read-only file system",I tried two other partitions, the result was the same. Yesterday before I tried with a flush with 16G, but I can write date into the mounted partition, who can tell me the reason, thank you very much!

All my operations was under the root