Re: linux raid vs hw raid

From	Grant <omg@grrr.id.au>
Newsgroups	comp.os.linux.misc
Subject	Re: linux raid vs hw raid
Date	2011-04-10 20:09 +1000
Organization	scattered bugs
Message-ID	<c503q6p85172iuonf0dbfoo1r8qt6srpgb@4ax.com> (permalink)
References	<fc0t68x5ci.ln2@goaway.wombat.san-francisco.ca.us> <4da02d29@news.broadpark.no> <slrniq2a2h.8od.spamtrap42@one.localnet>

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On 10 Apr 2011 03:47:29 GMT, Robert Riches <spamtrap42@jacob21819.net> wrote:

>On 2011-04-09, KR <kristian.rasmussen@broadpark.no.spam.com> wrote:
>> On 06.04.2011 04:39, Keith Keller wrote:
>>> 
>>> The obvious advantage to this is cost: I can save almost 40% of my
>>> original estimate by using desktop drives instead, thus fulfilling the
>>> original meaning of the I of the RAID acronym.  There are other
>>> advantages, as well, including being able to build a RAID6, which I
>>> slightly prefer over a RAID50, and having more flexibility later on if I
>>> want to move to bigger disks.  (Yes, I have seen the documentation
>>> warning against too-large RAID arrays resulting in a failure during a
>>> rebuild.)  A tertiary advantage would be that I would learn how to work
>>> with linux software RAID, a skill I haven't yet acquired.
>>
>> "Enterprise hard drives" can mean at least two different things: either
>> the drives are high-performance SATA or SAS drives (10k or 15k RPM), or
>> they are regular high-end (7.2k RPM) SATA drives with non-sequential
>> serial numbers.
>>
>> In the latter case, the drives are really regular desktop drives,
>> sometimes fitted with slightly more cache, but the drives are from
>> different batches. This saves you from experiencing multiple drive
>> failures over a short time period due to some manufacturing defect.
>
>I researched RAID a couple of months ago and found a lot of
>references that indicated something akin to a 'limited duration
>recalibration' (or similar wording) that is generally a feature
>of enterprise- or raid-edition disks but not of desktop units.
>The idea is a desktop disk can go out to lunch for several
>seconds to recalibrate itself, long enough to cause the RAID
>controller (or mdadm or LVM) to declare the physical disk drive
>to be dead.
>
>Are you saying 7200rpm disk drives have no such difference
>between desktop varieties and enterprise- or raid-edition models?

The whole point of RAID is to get reliability from cheap disks. 

I haven't noticed disks going "out to lunch" for years, these days they 
use embedded servo and that old style thermal calibration went out of 
use a decade or more ago.  

Grant.

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Thread

linux raid vs hw raid Keith Keller <kkeller-usenet@wombat.san-francisco.ca.us> - 2011-04-05 19:39 -0700
  Re: linux raid vs hw raid Tim Watts <tw@dionic.net> - 2011-04-06 08:01 +0100
    Re: linux raid vs hw raid David Brown <david@westcontrol.removethisbit.com> - 2011-04-06 10:03 +0200
      Re: linux raid vs hw raid Keith Keller <kkeller-usenet@wombat.san-francisco.ca.us> - 2011-04-06 14:00 -0700
        Re: linux raid vs hw raid David Brown <david.brown@removethis.hesbynett.no> - 2011-04-06 23:42 +0200
        Re: linux raid vs hw raid Grant <omg@grrr.id.au> - 2011-04-08 10:45 +1000
          Re: linux raid vs hw raid David Brown <david@westcontrol.removethisbit.com> - 2011-04-08 11:12 +0200
            Re: linux raid vs hw raid Keith Keller <kkeller-usenet@wombat.san-francisco.ca.us> - 2011-04-08 08:22 -0700
              Re: linux raid vs hw raid Grant <omg@grrr.id.au> - 2011-04-09 09:51 +1000
                Re: linux raid vs hw raid Keith Keller <kkeller-usenet@wombat.san-francisco.ca.us> - 2011-04-08 17:10 -0700
                Re: linux raid vs hw raid David Brown <david.brown@removethis.hesbynett.no> - 2011-04-09 13:14 +0200
            Re: linux raid vs hw raid Grant <omg@grrr.id.au> - 2011-04-09 09:47 +1000
              Re: linux raid vs hw raid David Brown <david.brown@removethis.hesbynett.no> - 2011-04-09 13:55 +0200
          Re: linux raid vs hw raid Tris Orendorff <triso@remove-me.cogeco.ca> - 2011-04-12 18:04 +0000
            Re: linux raid vs hw raid Keith Keller <kkeller-usenet@wombat.san-francisco.ca.us> - 2011-04-12 11:34 -0700
              Re: linux raid vs hw raid The Natural Philosopher <tnp@invalid.invalid> - 2011-04-12 21:13 +0100
                Re: linux raid vs hw raid David Brown <david@westcontrol.removethisbit.com> - 2011-04-13 09:45 +0200
                Re: linux raid vs hw raid Grant <omg@grrr.id.au> - 2011-04-14 13:42 +1000
                Re: linux raid vs hw raid David Brown <david@westcontrol.removethisbit.com> - 2011-04-14 09:15 +0200
                Re: linux raid vs hw raid Grant <omg@grrr.id.au> - 2011-04-15 08:03 +1000
                Re: linux raid vs hw raid Tim Watts <tw@dionic.net> - 2011-04-15 07:22 +0100
                Re: linux raid vs hw raid David Brown <david@westcontrol.removethisbit.com> - 2011-04-15 09:28 +0200
                Re: linux raid vs hw raid Grant <omg@grrr.id.au> - 2011-04-19 11:20 +1000
              Re: linux raid vs hw raid Grant <omg@grrr.id.au> - 2011-04-14 13:38 +1000
                Re: linux raid vs hw raid Keith Keller <kkeller-usenet@wombat.san-francisco.ca.us> - 2011-04-13 21:49 -0700
            Re: linux raid vs hw raid Grant <omg@grrr.id.au> - 2011-04-14 13:34 +1000
              Re: linux raid vs hw raid Tris Orendorff <triso@remove-me.cogeco.ca> - 2011-04-15 21:59 +0000
                Re: linux raid vs hw raid "Peter J. Holzer" <hjp-usenet2@hjp.at> - 2011-04-16 00:56 +0200
                Re: linux raid vs hw raid The Natural Philosopher <tnp@invalid.invalid> - 2011-04-16 01:32 +0100
  Re: linux raid vs hw raid Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2011-04-08 21:38 +0300
    Re: linux raid vs hw raid Grant <omg@grrr.id.au> - 2011-04-09 09:53 +1000
  Re: linux raid vs hw raid KR <kristian.rasmussen@broadpark.no.spam.com> - 2011-04-09 11:56 +0200
    Re: linux raid vs hw raid Keith Keller <kkeller-usenet@wombat.san-francisco.ca.us> - 2011-04-09 10:32 -0700
      Re: linux raid vs hw raid Grant <omg@grrr.id.au> - 2011-04-10 11:12 +1000
        Re: linux raid vs hw raid Keith Keller <kkeller-usenet@wombat.san-francisco.ca.us> - 2011-04-09 18:59 -0700
          Re: linux raid vs hw raid KR <kristian.rasmussen@broadpark.no.spam.com> - 2011-04-10 04:32 +0200
            Re: linux raid vs hw raid Grant <omg@grrr.id.au> - 2011-04-10 12:46 +1000
              Re: linux raid vs hw raid Keith Keller <kkeller-usenet@wombat.san-francisco.ca.us> - 2011-04-09 20:39 -0700
    Re: linux raid vs hw raid Robert Riches <spamtrap42@jacob21819.net> - 2011-04-10 03:47 +0000
      Re: linux raid vs hw raid Balwinder S Dheeman <bsd.SANSPAM@anu.homelinux.net> - 2011-04-10 11:11 +0530
        Re: linux raid vs hw raid Keith Keller <kkeller-usenet@wombat.san-francisco.ca.us> - 2011-04-09 23:29 -0700
          Re: linux raid vs hw raid Balwinder S Dheeman <bsd.SANSPAM@anu.homelinux.net> - 2011-04-10 14:05 +0530
        Re: linux raid vs hw raid Grant <omg@grrr.id.au> - 2011-04-10 20:16 +1000
          Re: linux raid vs hw raid Tim Watts <tw@dionic.net> - 2011-04-10 11:28 +0100
          Re: linux raid vs hw raid Balwinder S Dheeman <bsd.SANSPAM@anu.homelinux.net> - 2011-04-10 19:43 +0530
        Re: linux raid vs hw raid Robert Riches <spamtrap42@jacob21819.net> - 2011-04-12 03:44 +0000
          Re: linux raid vs hw raid Balwinder S Dheeman <bsd.SANSPAM@anu.homelinux.net> - 2011-04-12 13:56 +0530
      Re: linux raid vs hw raid Grant <omg@grrr.id.au> - 2011-04-10 20:09 +1000
        Re: linux raid vs hw raid Robert Riches <spamtrap42@jacob21819.net> - 2011-04-12 03:37 +0000

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