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Brad Fitzpatrick

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RAID-6 votes Bush [Jan. 12th, 2004|01:46 am]
Brad Fitzpatrick
Heh....

diff -puN drivers/md/Kconfig~raid6-20040107 drivers/md/Kconfig
--- 25/drivers/md/Kconfig~raid6-20040107 2004-01-08 00:26:29.000000000 -0800
+++ 25-akpm/drivers/md/Kconfig 2004-01-08 00:26:29.000000000 -0800
@@ -107,6 +107,39 @@ config MD_RAID5

If unsure, say Y.

+config MD_RAID6
+ tristate "RAID-6 mode (EXPERIMENTAL)"
+ depends on BLK_DEV_MD && EXPERIMENTAL
+ ---help---
+ WARNING: RAID-6 is currently highly experimental. If you
+ use it, there is no guarantee whatsoever that it won't
+ destroy your data, eat your disk drives, insult your mother,
+ or re-appoint George W. Bush.

+

....

(yeah, I can't sleep... what's new?)
LinkReply

Comments:
[User Picture]From: funjon
2004-01-12 03:56 pm (UTC)
What the heck is RAID-6?!

I definitely don't want it if it'll insult Mom.
(Reply) (Thread)
[User Picture]From: xunker
2004-01-12 07:06 pm (UTC)
IIRC, it's Raid 5 + 1. I know that sounds simplistic, but that's what it is: In a raid 5 array you can lose one drive and still keep the array functioning -- in raid 6, you can lose two drives, though it gives a larger performance hit because it has to compute some extra parity calculations.
(Reply) (Parent) (Thread)
(Deleted comment)
[User Picture]From: brad
2004-01-12 09:11 pm (UTC)
No, no... raid 10 isn't 5+1. raid 10 is 1+0.
(Reply) (Parent) (Thread)
From: (Anonymous)
2004-10-25 01:39 am (UTC)
RAID 10 is not 1+0

in RAID 10 you create mirror arrays and then stripe them. In raid 0+1 you stripe date and then mirror it.

RAID 10
| array 1 | - | array 2 |
----- ----- ----- -----
| A | | A | - | B | | B |
| C | | C | - | D | | D |
| E | | E | - | F | | F |
----- ----- ----- -----
| RAID 1 | - | RAID 1 |
|------ RAID 0 -------|

RAID 0+1
|----- array -------|
----- ----- ----- ----
| A | | B | | C | | D | stripe -|
| D | | A | | B | | C | -------|mirror
| E | | F | | G | | H |
| H | | E | | F | | G |

this is equivalent to RAID 50 and RAID 5+1. RAID 0+1 is also implemented in a sligthly different form.

The advantage of RAID 0+1 is READ performance (similar to RAID 0 with same amount of drives) and you can use it also with unequal amounts of disks (3 and plus)

dietmarh
(Reply) (Parent) (Thread)
[User Picture]From: xunker
2004-01-12 09:51 pm (UTC)
I didn't mean "5+1" as in "5+1", I meant it as is "add one to 5 and you get 6".. and usually RAID 10 means mirrored Raid 0, right? (and Raid 01 means striped/spanned raid 1, right?)
(Reply) (Parent) (Thread)
(Deleted comment)
From: (Anonymous)
2004-01-27 12:25 pm (UTC)

RAID-6

RAID-6 has two parity stripes, and so can lose two drives in an array simultaneously without losing data. RAID-5 can only lose one at once.
(Reply) (Parent) (Thread)
[User Picture]From: taral
2004-01-12 04:53 pm (UTC)
Where do I get that patchset?
(Reply) (Thread)
[User Picture]From: brad
2004-01-12 05:32 pm (UTC)
2.6.1-mm1
(Reply) (Parent) (Thread)