Re: `Secure' deletion in zfs

Tim Bradshaw <tfb+google@xxxxxxxx> wrote:
There are various utilities which make attempts to securely delete
files, typically by overwriting them multiple times with random junk
and then deleting them. Regardless of how secure this actually is
given all the places the data might end up even on traditional
filesystems, am I right that copy-on-write basically dooms this
completely on zfs?

Looks that way. Especially since they wouldn't be aware of any
snapshots that might be present.

If I wanted to make a reasonably good promise that
the blocks that once held some data no longer do, how should I do this
with zfs?

#1. Put support into the filesystem. Maybe have a filesystem option
that all freed blocks get overwritten several times (either sync or
async). Potentially, this could even be done on a file-by-file
basis.

#2. Delete the file, delete any snapshots potentially holding blocks
with that information, then overwrite all free blocks (but you
can't really do that multiple times easily).

--
Darren Dunham ddunham@xxxxxxxx
Senior Technical Consultant TAOS http://www.taos.com/
Got some Dr Pepper? San Francisco, CA bay area
< This line left intentionally blank to confuse you. >
.

Relevant Pages

  • Re: undo rm deleteing /etc very urgent
    ... To prevent overwriting those "free" sectors where /etc ... Shutdown the machine if dismount is not possible. ... > filesystem /etc was stored on. ... To unsubscribe: http://www.redhat.com/mailman/listinfo/fedora-list ...
    (Fedora)
  • Re: Erasing a file
    ... overwrite it multiple times, ... very sophisticated equipment can recover erased data. ... overwriting even once is good enough. ... Even deleting without ...
    (microsoft.public.windowsxp.general)
  • Re: Memory management on Sun Solaris
    ... Bernd Haug wrote: ... >>will not be written to swap, but are read again from the filesystem ... it removes the link to the inode from the directory. ... Overwriting is a different issue. ...
    (comp.unix.solaris)
  • Re: Erasing HD - really erasing it.
    ... I have heard that there are utilities that "truly" erase an ... overwriting existing data with "X" and doing so ... multiple times. ... I use BCWipe.On the web site it refers to 30-day trials of all their ...
    (microsoft.public.windowsxp.general)
  • Re: Erasing HD - really erasing it.
    ... "truly" erase an entire hard drive... ... overwriting existing data ... overwrite the drive with 0's - multiple times. ... Many other free drive wiping utilities. ...
    (microsoft.public.windowsxp.general)
Loading