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From: Tomasz Chmielewski <mangoo@wpkg.org>
To: linux-raid@vger.kernel.org
Subject: RAID-10 and 4 HDDs - how many HDDs can break without loosing data?
Date: Thu, 10 Aug 2006 10:48:01 +0200	[thread overview]
Message-ID: <44DAF2C1.2050308@wpkg.org> (raw)

I want to set up RAID-10 on 4 400 GB drives, on not-so powerful machine 
(600 MHz ARM, Thecus n4100) - to have a total of 800 GB storage, with 
some protection against a drive failure.

As the machine is not very powerful, I don't want to use RAID-5 nor RAID-6.


Previously, I would use RAID-0 on top of two RAID-1s:

     ----RAID0----
     |           |
   RAID1       RAID1
  |    |       |    |
HDD1 HDD2   HDD3 HDD4


With RAID-0 on top of RAID-1, with 4 drives, I would achieve:
- 100% chance of recovery if any single, one disk fails,
- 50% chance of recovery if any two disk failure.


Now with RAID-10 in the Linux kernel, what are my chances of recovering 
from a single and two disk failure?

        RAID10
  ------------------
  |    |      |    |
HDD1 HDD2  HDD3 HDD4

Is it also 100% if one disk fails, and 50% if two disks fail?

Or perhaps, with 4 drives, RAID-10 can survive any 2 disks failure?


-- 
Tomasz Chmielewski
http://wpkg.org

             reply	other threads:[~2006-08-10  8:48 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-08-10  8:48 Tomasz Chmielewski [this message]
2006-08-14 21:48 ` RAID-10 and 4 HDDs - how many HDDs can break without loosing data? Andrew Rechenberg Lists
  -- strict thread matches above, loose matches on Subject: below --
2006-08-10  8:49 Tomasz Chmielewski
2006-08-10 10:39 ` Luca Berra

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