From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ric Wheeler <rwheeler@redhat.com>
Subject: Re: Btrfs: broken file system design (was Unbound(?) internal fragmentation
 in Btrfs)
Date: Sat, 26 Jun 2010 07:55:48 -0400
Message-ID: <4C25EAC4.1040909@redhat.com>
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Cc: Daniel Taylor <Daniel.Taylor@wdc.com>,
	Mike Fedyk <mfedyk@mikefedyk.com>,
	Daniel J Blueman <daniel.blueman@gmail.com>,
	Mat <jackdachef@gmail.com>, LKML <linux-kernel@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org,
	Chris Mason <chris.mason@oracle.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	The development of BTRFS <linux-btrfs@vger.kernel.org>
To: Michael Tokarev <mjt@tls.msk.ru>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <4C258D91.6010308@msgid.tls.msk.ru>
List-ID: <linux-btrfs.vger.kernel.org>

On 06/26/2010 01:18 AM, Michael Tokarev wrote:
> 25.06.2010 22:58, Ric Wheeler wrote:
>    
>> On 06/24/2010 06:06 PM, Daniel Taylor wrote:
>>      
> []
>    
>>>> On Wed, Jun 23, 2010 at 8:43 PM, Daniel Taylor
>>>> <Daniel.Taylor@wdc.com>   wrote:
>>>>
>>>>          
>>>>> Just an FYI reminder.  The original test (2K files) is utterly
>>>>> pathological for disk drives with 4K physical sectors, such as
>>>>> those now shipping from WD, Seagate, and others.  Some of the
>>>>> SSDs have larger (16K0 or smaller blocks (2K).  There is also
>>>>> the issue of btrfs over RAID (which I know is not entirely
>>>>> sensible, but which will happen).
>>>>>            
> Why it is not sensible to use btrfs on raid devices?
> Nowadays raid is just everywhere, from 'fakeraid' on AHCI to
> large external arrays on iSCSI-attached storage.  Sometimes
> it is nearly imposisble to _not_ use RAID, -- many servers
> comes with a built-in RAID card which can't be turned off or
> disabled.  And hardware raid is faster (at least in theory)
> at least because it puts less load on various system busses.
>
> To many "enterprise folks" a statement "we don't need hw raid,
> we have better solution" sounds like "we're just a toy, don't
> use".
>
> Hmm?  ;)
>
> /mjt, who always used and preferred _software_ raid due to
>   multiple reasons, and never used btrfs so far.
>    

Absolutely no reason that you would not use btrfs on hardware raid 
volumes (or software RAID for that matter).

Ric