[libvirt] [PATCH] virStorageVolWipe: Document that wiping journaled FS is useless

[Michal Privoznik]

On 21.12.2015 11:20, Vasiliy Tolstov wrote:
> 2015-12-21 10:18 GMT+03:00 Michal Privoznik <mprivozn at redhat.com>:
>> None that I know of. It's just that I've came across some discussion in
>> the office about volWipe and it just appeared to me that we ought to
>> have this documented.
> 
> 
> May be in this case doing FITRIM ioctl ? As i understand this ioctl
> can get minimal amount of space that needed to trim, so specify the
> file size we can hope that volume wiped..
> 

I'm no expert but I think fstrim is no help here - it merely reclaims
free space on a disk, but raw data is still accessible. At least can be
if disk does not implement DRAT (Deterministic Read After Trim) (read of
zeroes that is).

But better safe than sorry, right? So maybe we should issue fstrim after
all.

Michal