From: Bill Davidsen <davidsen@tmr.com>
To: "Michał Sawicz" <michal@sawicz.net>
Cc: linux-raid <linux-raid@vger.kernel.org>
Subject: Re: Building RAID5 w/o a Hot Spare
Date: Mon, 01 Feb 2010 16:45:48 -0500 [thread overview]
Message-ID: <4B674B8C.9010200@tmr.com> (raw)
In-Reply-To: <1264603577.1928.4.camel@test.apertos.eu>
Michał Sawicz wrote:
> Dnia 2010-01-27, śro o godzinie 09:26 -0500, Carlos Williams pisze:
>
>> I am building a Linux system which has 4 identical 'fd' partitions on
>> each of the 4 drives. I don't want to use the 4th partition or disk if
>> you would like to call it as a 'hot spare'. I would like to span the
>> entire array over the 4 drives. My question is does my command look
>> correct for doing so?
>>
>
> I'm not sure I understand what you want to achieve. A 'spare' disk is
> one that isn't used until any of the other fail, then the spare replaces
> the failed one. The term 'hot spare' is used to identify a disk that is
> a mirror of one of the other drives, but there's no support for that in
> Linux Software-RAID.
>
>
>> mdadm --create /dev/md0 --level=5 --raid-devices=4 /dev/sda2 /dev/sdb2
>> /dev/sdc2 /dev/sdd2
>>
>
> This will create a RAID5 array of 4 devices, yes. Capacity will be 3 x
> sd?2. Failure of any one of those disks will not harm the data.
>
>
A hot spare is in and spinning, or at least powered up, ready to use
with software. And software raid does support putting a raid, such as
raid-1 or even raid-5, or members which are raid-1 with a write mostly
drive and ready to go.
--
Bill Davidsen <davidsen@tmr.com>
"We can't solve today's problems by using the same thinking we
used in creating them." - Einstein
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next prev parent reply other threads:[~2010-02-01 21:45 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-27 14:26 Building RAID5 w/o a Hot Spare Carlos Williams
2010-01-27 14:46 ` Michał Sawicz
2010-01-27 14:53 ` Robin Hill
2010-02-01 21:45 ` Bill Davidsen [this message]
2010-01-27 15:14 ` Goswin von Brederlow
2010-01-27 15:15 ` Carlos Williams
2010-01-27 20:46 ` Goswin von Brederlow
[not found] ` <1264603005.1928.3.camel@test.apertos.eu>
[not found] ` <d80f793f1001270641k29430f12r59b9f9fa02966ea0@mail.gmail.com>
2010-01-27 14:49 ` Carlos Williams
2010-01-27 15:34 ` Michał Sawicz
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