From: John Robinson <john.robinson@anonymous.org.uk>
To: Asdo <asdo@shiftmail.org>
Cc: linux-raid <linux-raid@vger.kernel.org>
Subject: Re: First raid1 sector gets zeroed at first reboot
Date: Wed, 17 Aug 2011 15:34:46 +0100 [thread overview]
Message-ID: <4E4BD186.4070604@anonymous.org.uk> (raw)
In-Reply-To: <4E4BC96D.1020802@shiftmail.org>
On 17/08/2011 15:00, Asdo wrote:
> On 08/17/11 15:43, John Robinson wrote:
>>
>> The first sector of a md RAID with metadata 1.0 is in its data area,
>> so there's no way md is writing to this area itself, it's almost
>> certainly the filesystem that's writing it.
>>
>> I think installing grub on a md partition is a bad idea. You can use
>> metadata 1.2 to have the first 4K left free, but grub may write its
>> stage 1.5 code to the first 31.5K of a device (whole drive or partition).
>>
>
> No you are confusing it with metadata 1.1 .
> Metadata 1.0 has the data at the end like 0.9 .
No I'm afraid it's you that's confused. Metadata 1.0 has the *metadata*
at the end, like 0.9, so it has the data i.e. filesystem area at the
beginning. Take a look with mdadm -D, the data offset is zero.
This is why partitions with 0.9 or 1.0 metadata in RAID-1 can be used
individually to boot from because the partitions look identical to ones
that just have filesystems on them.
Cheers,
John.
next prev parent reply other threads:[~2011-08-17 14:34 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-16 17:42 First raid1 sector gets zeroed at first reboot Asdo
2011-08-17 13:43 ` John Robinson
2011-08-17 14:00 ` Asdo
2011-08-17 14:34 ` John Robinson [this message]
2011-08-17 16:45 ` Asdo
2011-08-17 17:32 ` John Robinson
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