From: "Yan Zheng" <yanzheng@21cn.com>
To: "Chris Samuel" <chris@csamuel.org>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: multiple device usage
Date: Mon, 29 Dec 2008 23:16:33 +0800 [thread overview]
Message-ID: <3d0408630812290716i5ac68b27i17fe35891706e449@mail.gmail.com> (raw)
In-Reply-To: <200812292352.33059.chris@csamuel.org>
2008/12/29 Chris Samuel <chris@csamuel.org>:
> Hello Yan,
>
> On Mon, 29 Dec 2008 11:33:18 pm Yan Zheng wrote:
>
>> 2008/12/29 Chris Samuel <chris@csamuel.org>:
>>
>> > The rebalancing code does appear (from a naive read of the code) to be
>> > able to rebalance over stripes, but I have no idea if the disk format
>> > currently supports changing that on the fly.
>>
>> The rebalancing moves data/metadata to newly created chunks. If there
>> are two devices, the new chunks will be set up as RAID-1 by default.
>
> Very interesting! I didn't realise that - I was presuming that the
> BTRFS_BLOCK_GROUP_RAID1 ioctl needed to be passed through (as at mkfs time) to
> change it into a RAID1 array.
>
See __btrfs_reserve_extent and __btrfs_alloc_chunk. There is a mistake in
my previous reply. Only metadata chunks are set up as RAID-1 by default
when there are two devices.
Regards
Yan Zheng
next prev parent reply other threads:[~2008-12-29 15:16 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-26 23:15 multiple device usage devzero
2008-12-27 2:44 ` Yan Zheng
2008-12-27 14:12 ` Roland
2008-12-28 13:26 ` yanhai zhu
2008-12-29 10:49 ` Stephan von Krawczynski
2008-12-29 12:31 ` Roland
2008-12-29 12:35 ` Yan Zheng
2008-12-30 21:43 ` Chris Mason
2008-12-27 6:45 ` Chris Samuel
2008-12-29 11:32 ` Chris Samuel
2008-12-29 12:33 ` Yan Zheng
2008-12-29 12:52 ` Chris Samuel
2008-12-29 15:16 ` Yan Zheng [this message]
2008-12-30 21:25 ` Chris Mason
2009-01-01 1:02 ` Chris Samuel
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