I plan to reformat & reinstall my linux (centos).
Before doing this, I got to backup my files into my USB external hard disk from Seagate (FreeAgent).

The problem I faced is that I could not copy file into the hard disk even I was in root user. It prompted me that it is only read-only. I just wonder why...

I have tested with my thumb drive. It worked.

May I know why I could not copy file to the USB FreeAgent hard disk. Due to file system?

FYI. the file is a tar file xx.tar


Is it because the USB Seagate FreeAgent hard disk got window system? I am not sure...

Yes, it is most likely due to the filesystem. I recommend you run fsck with the command:
This will correct any errors you may have in the filesystem. "fsck" should automatically detect the type of filesystem, by the way. If you can, please post the type of filesystem that is on the USB disk. Sometimes, NTFS formatted drives are mounted read-only. In this case, you should either force it to mount read-write (this may need to be enabled in the kernel), or just reformat the drive to a different filesystem. To reformat the drive as FAT32, use:
To format it as EXT3, use:
Hope this helps!

[root@circuit media]# mount
/dev/sda6 on / type ext3 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
tmpfs on /dev/shm type tmpfs (rw)
/dev/sda8 on /app type ext3 (rw)
/dev/sda3 on /mnt/win_c type fuseblk (rw,allow_other,blksize=4096)
/dev/sda5 on /mnt/win_f type fuseblk (rw,allow_other,blksize=4096)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
/dev/sdb1 on /media/FreeAgent Drive type ntfs (rw,noexec,nosuid,nodev,umask=222)

----------------------------------------------

[root@circuit media]# /sbin/fsck /dev/sdb1
fsck 1.39 (29-May-2006)
fsck: fsck.ntfs: not found
/sbin/fsck: Error 2 while executing fsck.ntfs for /dev/sdb1

------------------------------------------------

So what does it mean? no write access in linux?

I have backed up all my window vista document to the freeagent hard disk. It works! But it does not work when copy from linux OS. Why so complicated...

PS: I dont want to format my external harddisk since I also backup my window doc

Hmmm... Maybe you could try this website: http://www.linux-ntfs.org
There are some utilities for working with NTFS disks on that site. The RPM download available there is for Red Hat / Fedora, so it may not work with CentOS. You could still try it. Or, you could check your distribution's repository for the program: "ntfsprogs". These utilities should help you mount the disk properly.