linux-kernel - Re: writeback cache dangers Re: [ANNOUNCE] Ramback: faster than a speeding bullet

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20080314192912.GB13733@mit.edu>
Date:	Fri, 14 Mar 2008 15:29:12 -0400
From:	Theodore Tso <tytso@....edu>
To:	Pavel Machek <pavel@....cz>
Cc:	Ric Wheeler <ric@....com>, Benny Amorsen <benny+usenet@...rsen.dk>,
	linux-kernel@...r.kernel.org
Subject: Re: writeback cache dangers Re: [ANNOUNCE] Ramback: faster than a
	speeding bullet

On Fri, Mar 14, 2008 at 08:03:57PM +0100, Pavel Machek wrote:
> 
> > The ingest rate at the time of a power hit makes a huge 
> > difference as well - basically, pulling the power cord 
> > when a box is idle is normally not harmful. Try that 
> > when you are really pounding on the disks and you will 
> > see corruptions a plenty without barriers ;-)
> 
> I tried that, and could not get a corrruption. cp -a on big kernel
> trees, on sata disk with writeback cache and no barriers... and I
> could not cause fs corruption. ext3.
> 
> I'd like to demo danger of writeback cache. What should I do?

Ext3's journal probably hides a huge number of problems.  I'd try
something with a lot more parallel modifications to metadata.  Say
postmark with a large number of threads.  It would be interesting
actually to get some controlled results of exactly how busy a
filesystem has to be before you get filesystem corruption (which I
would check explicitly running "e2fsck -f" e2fsck after pulling the
plug on the drive).

					- Ted
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/