how to make my RAID device WORM(write once and read many)

[Roland Smith]

On Mon, Apr 18, 2005 at 09:27:48AM -0400, Lowell Gilbert wrote:
> Please don't top-post.
> 
> prasadam kumar <prasadamkumar at yahoo.com> writes:
> 
> > Thanks for responding to my query,
> > actually it is a raid5 storage device it contains
> > firewire and usb ports, through this
> > interface a user can store data to the  raid5 device
> > irrespective of file system.
> > once he copied data to the device it should be
> > immutable(i.e cannot be modify and delete).
> > Can u suggest any approach to achieve this task.

If it's OK to invoke a shell-script to do the archiving, and if you're
using UFS it would be possible, I think. That script should do the following:

- check for name clashes (abort with an error if a file already exists).
- copy the file to the target disk.
- chmod ugo-w the file to remove all write permissions.
- chflags schg,sunlnk,uchg,uunlnk <file>

Of course this is not foolproof, because the superuser can change the
flags and permissions.

Another option would be to use a revision control system that can handle
arbitrary files like subversion. If you write ("commit") a new version
of a file, the old version is not lost. This also supposes that you
create a wrapper script to make things easier (because the first write
has to be an "add" rather than a "commit", and other details like
creating directories etc).

Roland
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