from man shred

Weblog:		Please, For the Love of All That's Recoverable, Shred Your Hard Drive!
Subject:		from man shred
Date:		2005-03-04 06:47:03
From:		markybob

Since shred writes on such a low-level, it doesn't actually matter what kind of filesystem is on the partition [snip...] CAUTION: Note that shred relies on a very important assumption: that the filesystem overwrites data in place. This is the traditional way to do things, but many modern filesystem designs do not satisfy this assumption. The following are examples of filesystems on which shred is not effective: * log-structured or journaled filesystems, such as those supplied with AIX and Solaris (and JFS, ReiserFS, XFS, Ext3, etc.) * filesystems that write redundant data and carry on even if some writes fail, such as RAID-based filesystems * filesystems that make snapshots, such as Network Appliance's NFS server * filesystems that cache in temporary locations, such as NFS version 3 clients * compressed filesystems

Showing messages 1 through 3 of 3.

from man shred
2005-03-04 08:56:49 Kyle Rankin |

[Reply | View]

I think you have misunderstood me. You are talking about using shred when overwriting a single file. I'm talking about using shred to write bit-by-bit over an entire partition. From the shred info page:



Generally speaking, it is more reliable to shred a device than a file, since this bypasses the problem of filesystem design mentioned above.  However, even shredding devices is not always  completely reliable.  For example, most disks map out bad sectors invisibly to the application; if the bad sectors contain sensitive data, `shred' won't be able to destroy it.

from man shred
2005-03-31 17:50:12 EnigmaCurry [Reply | View]

I assume that since you pasted part of the man page from shred you assume that the article's method does not work on filesystems like JFS, ReiserFS, XFS, Ext3, etc.

This is completely incorrect. The article's method works great _no_matter_what_filesystem is used on the hard drive.

What the man page is saying is that it cannot gurantee that a individual _file_ can be erased on journaling filesystems. Since we're shredding the entire filesystem this is a non-issue.

from man shred
2005-03-31 17:51:44 EnigmaCurry [Reply | View]

whoops, didn't realize this topic was already addressed. It didn't show the thread on the main page. :)

Showing messages 1 through 3 of 3.