Re: Btrfs: broken file system design (was Unbound(?) internal fragmentationin Btrfs)

[Ric Wheeler]

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@xxxxxxx>   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

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