From: Chris Mason <chris.mason@oracle.com>
To: Andreas Dilger <adilger@sun.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Christoph Hellwig <hch@infradead.org>,
sfr@canb.auug.org.au, linux-kernel@vger.kernel.org,
linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: Notes on support for multiple devices for a single filesystem
Date: Wed, 17 Dec 2008 16:41:58 -0500 [thread overview]
Message-ID: <1229550118.27170.103.camel@think.oraclecorp.com> (raw)
In-Reply-To: <20081217212409.GB5000@webber.adilger.int>
On Wed, 2008-12-17 at 14:24 -0700, Andreas Dilger wrote:
> I can't speak for btrfs, but I don't think multiple device access from
> the filesystem is a "layering violation" as some people comment. It
> is
> just a different type of layering. With ZFS there is a distinct layer
> that is handling the allocation, redundancy, and transactions (SPA,
> DMU)
> that is exporting an object interface, and the filesystem (ZPL, or
> future
> versions of Lustre) is built on top of that object interface.
Clean interfaces aren't really my best talent, but btrfs also layers
this out. logical->physical mappings happen in a centralized function,
and all of the on disk structures use logical block numbers.
The only exception to that rule is the superblock offsets on the device.
-chris
next prev parent reply other threads:[~2008-12-17 21:41 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-11-20 12:18 Btrfs trees for linux-next Chris Mason
2008-12-11 2:34 ` Chris Mason
2008-12-11 3:14 ` Stephen Rothwell
2008-12-11 4:06 ` Andrew Morton
2008-12-11 5:55 ` Stephen Rothwell
2008-12-11 14:43 ` Chris Mason
2008-12-15 21:03 ` Andreas Dilger
2008-12-15 22:55 ` Kay Sievers
2008-12-16 1:37 ` Chris Mason
2008-12-16 1:39 ` Kay Sievers
2008-12-17 13:23 ` Notes on support for multiple devices for a single filesystem Christoph Hellwig
2008-12-17 14:50 ` Kay Sievers
2008-12-17 15:08 ` Christoph Hellwig
2008-12-17 15:33 ` Kay Sievers
2008-12-17 14:53 ` Chris Mason
2008-12-17 19:53 ` Andrew Morton
2008-12-17 20:58 ` Chris Mason
2008-12-17 21:20 ` Kay Sievers
2008-12-17 21:26 ` Chris Mason
2008-12-17 21:27 ` Jeff Garzik
2008-12-18 21:22 ` Bryan Henderson
2008-12-17 21:24 ` Andreas Dilger
2008-12-17 21:30 ` Jeff Garzik
2008-12-17 21:41 ` Chris Mason [this message]
2008-12-22 1:59 ` Liu Hui
2008-12-17 22:04 ` Andreas Dilger
2008-12-17 22:19 ` Dave Kleikamp
[not found] <e1f6055f0812181336q105b4ebcy81d72edd2a35baa8@mail.gmail.com>
2008-12-19 19:03 ` Bryan Henderson
2008-12-19 19:30 ` Chris Mason
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