From: David Brown <david.brown@hesbynett.no>
To: Chris Murphy <lists@colorremedies.com>
Cc: stan@hardwarefreak.com,
"linux-raid@vger.kernel.org list" <linux-raid@vger.kernel.org>
Subject: Re: Usefulness of RAID 4
Date: Wed, 20 Feb 2013 08:56:45 +0100 [thread overview]
Message-ID: <512481BD.1010903@hesbynett.no> (raw)
In-Reply-To: <CBC74AA5-EA3C-4B35-B43E-9C1F12C864CE@colorremedies.com>
On 19/02/13 23:46, Chris Murphy wrote:
>
> On Feb 19, 2013, at 3:41 PM, Stan Hoeppner <stan@hardwarefreak.com>
> wrote:
>
>> On 2/18/2013 9:01 PM, Chris Murphy wrote:
>>> Assuming HDD only, is there broad use case for RAID 4 that RAID 5
>>> isn't equally or better suited for?
>>>
>>> What about making the parity drive an SSD, keeping the other
>>> drives HDD?
Raid 4 has no good uses as a final format for a raid layout - raid 5 is
better in every way.
However, raid 4 /is/ useful as an intermediary format for md raid,
during operations like re-shaping and re-sizing. It is more like a raid
5 with an unusual parity layout (md raid also supports raid 6 with a
number of different parity layouts for the same reason).
>>
>> Why are you revisiting RAID-4?
>
> Because it's offered in Fedora 18's GUI installer.
Fedora is a distribution aimed at experienced users and tinkerers, so it
tends to include all sorts of weird opinions in the installer - simply
because Linux supports them. It will probably also have an option to
use the minix file system for your root file system.
>
>> It's dead tech, decades ago. It has no advantages over subsequent
>> RAID levels, yet significant handicap.
>
> That's what I thought. But is it remotely practical/useful to use
> HDDs for data drives, and one SSD as the parity drive to eliminate
> the parity write bottleneck of RAID 4?
>
>
> Chris Murphy-- To unsubscribe from this list: send the line
> "unsubscribe linux-raid" in the body of a message to
> majordomo@vger.kernel.org More majordomo info at
> http://vger.kernel.org/majordomo-info.html
>
next prev parent reply other threads:[~2013-02-20 7:56 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-19 3:01 Usefulness of RAID 4 Chris Murphy
2013-02-19 22:41 ` Stan Hoeppner
2013-02-19 22:46 ` Chris Murphy
2013-02-19 22:58 ` Stan Hoeppner
2013-02-19 23:07 ` Chris Murphy
2013-02-20 7:56 ` David Brown [this message]
2013-02-20 19:24 ` Chris Murphy
2013-02-20 18:15 ` Stan Hoeppner
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