From: Stan Hoeppner <stan@hardwarefreak.com>
To: David Brown <david.brown@hesbynett.no>,
James Plank <plank@cs.utk.edu>, Ric Wheeler <rwheeler@redhat.com>
Cc: Andrea Mazzoleni <amadvance@gmail.com>,
"H. Peter Anvin" <hpa@zytor.com>,
linux-raid@vger.kernel.org, linux-btrfs@vger.kernel.org,
David Smith <creamyfish@gmail.com>
Subject: Re: Triple parity and beyond
Date: Fri, 22 Nov 2013 02:38:19 -0600 [thread overview]
Message-ID: <528F17FB.60909@hardwarefreak.com> (raw)
In-Reply-To: <528DCD36.1060808@hesbynett.no>
On 11/21/2013 3:07 AM, David Brown wrote:
> For example, with 20 disks at 1 TB each, you can have:
All correct, and these are maximum redundancies.
Maximum:
> raid5 = 19TB, 1 disk redundancy
> raid6 = 18TB, 2 disk redundancy
> raid6.3 = 17TB, 3 disk redundancy
> raid6.4 = 16TB, 4 disk redundancy
> raid6.5 = 15TB, 5 disk redundancy
These are not fully correct, because only the minimums are stated. With
any mirror based array one can lose half the disks as long as no two are
in one mirror. The probability of a pair failing together is very low,
and this probability decreases even further as the number of drives in
the array increases. This is one of the many reasons RAID 10 has been
so popular for so many years.
Minimum:
> raid10 = 10TB, 1 disk redundancy
> raid15 = 8TB, 3 disk redundancy
> raid16 = 6TB, 5 disk redundancy
Maximum:
RAID 10 = 10 disk redundancy
RAID 15 = 11 disk redundancy
RAID 16 = 12 disk redundancy
Range:
RAID 10 = 1-10 disk redundancy
RAID 15 = 3-11 disk redundancy
RAID 16 = 5-12 disk redundancy
--
Stan
next prev parent reply other threads:[~2013-11-22 8:38 UTC|newest]
Thread overview: 104+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-18 22:08 Triple parity and beyond Andrea Mazzoleni
2013-11-18 22:12 ` H. Peter Anvin
2013-11-18 22:35 ` Andrea Mazzoleni
2013-11-18 23:25 ` H. Peter Anvin
2013-11-19 10:16 ` David Brown
2013-11-19 17:36 ` Andrea Mazzoleni
2013-11-19 22:51 ` Drew
2013-11-20 0:54 ` Chris Murphy
2013-11-20 1:23 ` John Williams
2013-11-20 10:35 ` David Brown
2013-11-20 10:31 ` David Brown
2013-11-20 18:09 ` John Williams
2013-11-20 18:44 ` Andrea Mazzoleni
2013-11-21 6:15 ` Stan Hoeppner
2013-11-21 8:32 ` David Brown
2013-11-20 18:34 ` Andrea Mazzoleni
2013-11-20 18:43 ` H. Peter Anvin
2013-11-20 18:56 ` Andrea Mazzoleni
2013-11-20 18:59 ` H. Peter Anvin
2013-11-20 21:21 ` Andrea Mazzoleni
2013-11-20 19:00 ` H. Peter Anvin
2013-11-20 21:04 ` Andrea Mazzoleni
2013-11-20 21:06 ` H. Peter Anvin
2013-11-21 8:36 ` David Brown
2013-11-19 17:28 ` Andrea Mazzoleni
2013-11-19 20:29 ` Ric Wheeler
2013-11-20 16:16 ` James Plank
2013-11-20 19:05 ` Andrea Mazzoleni
2013-11-20 19:10 ` H. Peter Anvin
2013-11-20 20:30 ` James Plank
2013-11-20 21:23 ` Andrea Mazzoleni
2013-11-27 2:50 ` ronnie sahlberg
2013-11-20 21:28 ` H. Peter Anvin
2013-11-21 1:28 ` Stan Hoeppner
2013-11-21 2:46 ` John Williams
2013-11-21 6:52 ` Stan Hoeppner
2013-11-21 7:05 ` John Williams
2013-11-21 22:57 ` Stan Hoeppner
2013-11-21 23:38 ` John Williams
2013-11-22 9:35 ` Stan Hoeppner
2013-11-22 11:24 ` joystick
2013-11-22 15:01 ` John Williams
2013-11-22 22:28 ` Stan Hoeppner
2013-11-22 23:07 ` NeilBrown
2013-11-23 3:46 ` Stan Hoeppner
2013-11-23 5:04 ` NeilBrown
2013-11-23 5:34 ` John Williams
2013-11-23 7:12 ` NeilBrown
2013-11-24 4:03 ` Stan Hoeppner
2013-11-24 5:14 ` John Williams
2013-11-24 21:13 ` Stan Hoeppner
2013-11-24 23:28 ` Rudy Zijlstra
2013-11-24 23:53 ` Alex Elsayed
2013-11-25 2:04 ` Stan Hoeppner
2013-11-25 4:48 ` Alex Elsayed
2013-11-25 9:15 ` David Brown
2013-11-24 5:19 ` Russell Coker
2013-11-24 21:44 ` Stan Hoeppner
2013-11-24 22:31 ` Mark Knecht
2013-11-25 2:14 ` Russell Coker
2013-11-25 9:20 ` David Brown
2013-11-21 8:08 ` joystick
2013-11-22 0:30 ` Stan Hoeppner
2013-11-22 0:33 ` H. Peter Anvin
2013-11-22 0:45 ` David Brown
2013-11-21 9:07 ` David Brown
2013-11-21 9:54 ` Adam Goryachev
2013-11-21 10:32 ` David Brown
2013-11-22 8:12 ` Russell Coker
2013-11-25 18:23 ` Pasi Kärkkäinen
2013-11-22 8:13 ` Stan Hoeppner
2013-11-22 13:15 ` David Brown
2013-11-22 16:07 ` Stan Hoeppner
2013-11-22 22:59 ` NeilBrown
2013-11-23 17:39 ` David Brown
2013-11-22 16:50 ` Mark Knecht
2013-11-22 19:51 ` Duncan
2013-11-22 8:38 ` Stan Hoeppner [this message]
2013-11-22 13:24 ` David Brown
2013-11-28 7:16 ` Stan Hoeppner
2013-11-28 7:36 ` Russell Coker
2013-11-28 9:56 ` David Brown
2013-11-30 7:32 ` Alex Elsayed
2013-12-01 15:37 ` Stan Hoeppner
2013-11-22 14:19 ` David Taylor
2013-11-21 19:56 ` Piergiorgio Sartor
2013-11-19 18:12 ` Piergiorgio Sartor
2013-11-20 10:44 ` David Brown
2013-11-20 21:59 ` Piergiorgio Sartor
2013-11-21 10:13 ` David Brown
2013-11-21 17:37 ` Goffredo Baroncelli
2013-11-21 20:05 ` Piergiorgio Sartor
2013-11-21 20:31 ` David Brown
2013-11-21 20:52 ` Piergiorgio Sartor
2013-11-22 0:32 ` David Brown
2013-11-22 20:32 ` Piergiorgio Sartor
2013-11-26 18:10 ` joystick
2013-11-20 21:38 ` Andrea Mazzoleni
2013-11-20 22:29 ` Piergiorgio Sartor
2013-11-23 7:55 ` Andrea Mazzoleni
2013-11-23 22:10 ` Piergiorgio Sartor
2013-11-24 9:39 ` Andrea Mazzoleni
-- strict thread matches above, loose matches on Subject: below --
2013-12-01 17:53 Richard Scobie
2013-12-02 4:30 ` Stan Hoeppner
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