From: Carlos Mennens <carloswill@gmail.com>
To: Mdadm <linux-raid@vger.kernel.org>
Subject: Re: RAID1 On 3 Drives
Date: Sat, 13 Mar 2010 18:18:48 -0500 [thread overview]
Message-ID: <d80f793f1003131518u2bfe77e9k52ef77e3d2c68360@mail.gmail.com> (raw)
In-Reply-To: <4B9C11FB.7040604@gmx.net>
I am glad I asked! Thanks for all the info. Now my question next is if
I am creating a 3 disk raid with a 1 disk spare, do I need to use any
special 'mdadm' parameters besides what u see below for /boot (Grub)?
# mdadm --create /dev/md0 --level=1 --raid-devices=3 /dev/sda1
/dev/sdb1 /dev/sdc1 --spare-devices=1 /dev/sdd1
Anything else I should add to the above command for my /boot partition?
On 3/13/10, Joachim Otahal <Jou@gmx.net> wrote:
> On Sun, Mar 14, 2010 at 12:06 AM, Carlos Mennens<carloswill@gmail.com>
> wrote:
>> I was told by my distributions Wiki page that Grub doesn't support
>> RAID 5 or RAID 6 so I would need to create a volume with three disks
>> and set the level to RAID 1:
>>
>> # mdadm --create /dev/md1 --level=1 --raid-devices=3 /dev/sda1
>> /dev/sdb1 /dev/sdc1 --spare-devices=1 /dev/sdd1
>>
>> Is this possible to mirror three identical drive partitions? I was
>> talking to some co-workers and was told that I could only pair two
>> drives on RAID 1.
>>
>> Can anyone please help me understand this?
>
> /boot must be RAID1 (or a normal partition), everything else can be
> RAIDwhatever. Grub has no problems reading /boot from a mirrors.
>
> It is possible to make RAID1 to use more than two drives and keep the all
> active. In your case it is a matter of "believe" whether a spare is better
> or actually using all four actively in your raid, I prefer the latter.
> I have heavily tested more than two only with files via loopback yet, two
> drive, three drives, four drives and more. It does work, the testfile
> generated out of urandom kept the correct hash value throughout all my sick
> testings.
> The quick test with three SATA drives worked too, but it was just for the
> fun to see whether grub pukes or works (works if you don't forget the grub
> setup for drive 2, 3 etc).
> My plan is: Use RAID1 with 4 drives (quad-mirroring) for /boot or / and
> raid10 or raid5 for the data upon my next linux server upgrade.
>
> Joachim Otahal
>
>
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--
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next prev parent reply other threads:[~2010-03-13 23:18 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-13 22:30 RAID1 On 3 Drives Joachim Otahal
2010-03-13 23:18 ` Carlos Mennens [this message]
2010-03-13 23:50 ` Bill Davidsen
2010-03-15 12:30 ` Carlos Mennens
2010-03-15 12:48 ` Majed B.
2010-03-15 14:47 ` Carlos Mennens
2010-03-15 16:05 ` Majed B.
2010-03-16 1:46 ` Keld Simonsen
2010-03-20 16:08 ` Bill Davidsen
-- strict thread matches above, loose matches on Subject: below --
2010-03-13 21:06 Carlos Mennens
2010-03-13 21:21 ` Majed B.
2010-03-13 21:24 ` Carlos Mennens
2010-03-14 21:09 ` Luca Berra
2010-03-13 21:45 ` Neil Brown
2010-03-13 21:26 ` Neil Brown
2010-03-13 21:31 ` Majed B.
2010-03-13 21:50 ` Neil Brown
2010-03-14 3:30 ` Majed B.
2010-03-14 1:22 ` thib
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