From: Pavel Machek Subject: Re: ext2/3: document conditions when reliable operation is possible Date: Mon, 23 Mar 2009 12:00:19 +0100 Message-ID: <20090323110019.GD17681@elf.ucw.cz> References: <20090312092114.GC6949@elf.ucw.cz> <200903121413.04434.rob@landley.net> <20090316123051.GJ2405@elf.ucw.cz> <20090316194057.GA27897@silver.sucs.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Rob Landley , kernel list , Andrew Morton , mtk.manpages@gmail.com, tytso@mit.edu, rdunlap@xenotime.net, linux-doc@vger.kernel.org, linux-ext4@vger.kernel.org To: Sitsofe Wheeler Return-path: Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:57888 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756063AbZCWK5h (ORCPT ); Mon, 23 Mar 2009 06:57:37 -0400 Content-Disposition: inline In-Reply-To: <20090316194057.GA27897@silver.sucs.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon 2009-03-16 19:40:57, Sitsofe Wheeler wrote: > On Mon, Mar 16, 2009 at 01:30:51PM +0100, Pavel Machek wrote: > > + Unfortunately, none of the cheap USB/SD flash cards I've seen > > + do behave like this, and are thus unsuitable for all Linux > > + filesystems I know. > > When you say Linux filesystems do you mean "filesystems originally > designed on Linux" or do you mean "filesystems that Linux supports"? "Linux filesystems I know" :-). No filesystem that Linux supports, AFAICT. > Additionally whatever the answer, people are going to need help > answering the "which is the least bad?" question and saying what's not > good without offering alternatives is only half helpful... People need > to put SOMETHING on these cheap (and not quite so cheap) > devices... The According to me, people should just AVOID those devices. I don't plan to point the "least bad"; its still bad. > > + hdparm -I reports disk features. If you have "Native > > + Command Queueing" is the feature you are looking for. > > The document makes it sound like nearly everything bar battery backed > hardware RAIDed SCSI disks (with perfect firmware) is bad - is this > the intent? Battery backed RAID should be ok, as should be plain single SATA drive. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html