rt/snapraid
1
0
Fork 0
mirror of https://github.com/amadvance/snapraid.git synced 2026-10-26 10:51:54 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions

Reviews the raid.c initial description.

Browse source
This commit is contained in:
Andrea Mazzoleni 2013-12-29 22:54:03 +01:00
parent 03482b84a6
commit cda356dc75
2 changed files with 10 additions and 31 deletions
Download patch file Download diff file Expand all files Collapse all files

38
raid/raid.c
View file

@ -15,35 +15,17 @@
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* Copyright notes:
*
* The RAID5 and RAID6 support was originally derived from the
* H. Peter Anvin paper "The mathematics of RAID-6" [1] and the
* libraid6 library, also by H. Peter Anvin, released with license
* "GPLv2 or any later version" inside the Linux Kernel 2.6.38.
*
* This support was later completely rewritten (many times), but
* the H. Peter Anvin's Copyright may still apply.
*
* The others RAID levels and the recovering based on matrix
* inversion is original work implemented from scratch.
*/
#include "internal.h"
#include "gf.h"
/*
* The RAID5 and RAID6 support is implemented using the Galois Field
* GF(2^8) with the primitive polynomial x^8 + x^4 + x^3 + x^2 + 1
* (285 decimal).
* This is a RAID implementation working in the Galois Field GF(2^8) with
* the primitive polynomial x^8 + x^4 + x^3 + x^2 + 1 (285 decimal), and
* supporting up to six parity levels.
*
* The parity P and Q of a set of N disk Di with 0<=i<N, is computed
* using the equations:
*
* P = sum(Di)
* Q = sum(2^i * Di) with 0<=i<N
*
* This approach is the same used by the Linux Kernel RAID, and by ZFS
* RAIDZ2, better described in the H. Peter Anvin paper "The mathematics
* of RAID-6" [1].
* For RAID5 and RAID6 it works as as described in the H. Peter Anvin's
* paper "The mathematics of RAID-6" [1]. Please refer to this paper for a
* complete explanation.
*
* To support triple parity, it was first evaluated and then dropped, an
* extension of the same approach, with additional parity coefficients set
@ -100,7 +82,6 @@
* 01 bb a6 d7 c7 07 ce 82 4a 2f a5 9b b6 60 f1 ad e7 f4 06 d2 df 2e...
* 01 97 7f 9c 7c 18 bd a2 58 1a da 74 70 a3 e5 47 29 07 f5 80 23 e9...
* 01 2b 3f cf 73 2c d6 ed cb 74 15 78 8a c1 17 c9 89 68 21 ab 76 3b...
* (see tables.h for the matrix with all the columns)
*
* This matrix supports 6 level of parity, one for each row, for up to 251
* data disks, one for each column, with all the 377,342,351,231 square
@ -190,9 +171,6 @@
* [5] Plank, "Screaming Fast Galois Field Arithmetic Using Intel SIMD Instructions", 2013
*/
#include "internal.h"
#include "gf.h"
/**
* Generator matrix currently used.
*/

3
speed.c
View file

@ -147,7 +147,8 @@ void speed(void)
printf("\n");
printf("Speed test using %u data buffers of %u bytes, for a total of %u KiB.\n", nd, size, nd * size / 1024);
printf("The reported value is the aggregate bandwidth of all data disks in MiB/s (not counting parity disks).\n");
printf("The reported value is the aggregate bandwidth of all data disks in MiB/s,\n");
printf("not counting parity disks.\n");
printf("\n");
printf("Memory write speed using the C memset() function:\n");