From: "Austin S. Hemmelgarn" <ahferroin7@gmail.com>
To: Qu Wenruo <quwenruo@cn.fujitsu.com>, btrfs <linux-btrfs@vger.kernel.org>
Subject: Re: About minimal device number for RAID5/6
Date: Mon, 15 Aug 2016 07:57:17 -0400 [thread overview]
Message-ID: <d27bad69-1041-7771-aff6-c15beb85fbb1@gmail.com> (raw)
In-Reply-To: <d87a7caa-d414-1dbc-7c7e-a051e382114a@cn.fujitsu.com>
On 2016-08-15 03:50, Qu Wenruo wrote:
> Hi,
>
> Recently I found that manpage of mkfs is saying minimal device number
> for RAID5 and RAID6 is 2 and 3.
>
> Personally speaking, although I understand that RAID5/6 only requires
> 1/2 devices for parity stripe, it is still quite strange behavior.
>
> Under most case, user use raid5/6 for striping AND parity. For 2 devices
> RAID5, it's just a more expensive RAID1.
>
> IMHO it's better to warn user about 2 devices RAID5 or 3 devices RAID6.
>
> Any comment is welcomed.
>
Based on looking at the code, we do in fact support 2/3 devices for
raid5/6 respectively.
Personally, I agree that we should warn when trying to do this, but I
absolutely don't think we should stop it from happening.
next prev parent reply other threads:[~2016-08-15 11:57 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-15 7:50 About minimal device number for RAID5/6 Qu Wenruo
2016-08-15 11:57 ` Austin S. Hemmelgarn [this message]
2016-08-15 14:08 ` Anand Jain
2016-08-15 14:10 ` Austin S. Hemmelgarn
2016-08-15 14:32 ` Anand Jain
2016-08-15 15:01 ` Austin S. Hemmelgarn
2016-08-15 18:30 ` Hugo Mills
2016-08-15 21:20 ` Henk Slager
2016-08-16 1:32 ` Qu Wenruo
2016-08-16 12:01 ` Austin S. Hemmelgarn
2016-08-15 13:58 ` Anand Jain
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