Hi,
I want to report that I recently implemented a support for
arbitrary number of parities that could be useful also for Linux
RAID and Btrfs, both currently limited to double parity.
In short, to generate the parity I use a Cauchy matrix specifically
built to be compatible with the existing Lin
at generate the Cauchy matrix with some
explanation in the comments at (see the set_cauchy() function) :
http://sourceforge.net/p/snapraid/code/ci/master/tree/mktables.c
Ciao,
Andrea
On Mon, Nov 18, 2013 at 11:12 PM, H. Peter Anvin wrote:
> On 11/18/2013 02:08 PM, Andrea Mazzoleni wrote:
>
ridge_University_Press%282006%29.pdf
(search for "Extended Cauchy")
Ciao,
Andrea
On Tue, Nov 19, 2013 at 12:25 AM, H. Peter Anvin wrote:
> On 11/18/2013 02:35 PM, Andrea Mazzoleni wrote:
>> Hi Peter,
>>
>> The Cauchy matrix has the mathematical property to always have itse
t;> On 11/18/2013 02:35 PM, Andrea Mazzoleni wrote:
>>> Hi Peter,
>>>
>>> The Cauchy matrix has the mathematical property to always have itself
>>> and all submatrices not singular. So, we are sure that we can always
>>> solve the equations to recover
Hi David,
>> The choice of ZFS to use powers of 4 was likely not optimal,
>> because to multiply by 4, it has to do two multiplications by 2.
> I can agree with that. I didn't copy ZFS's choice here
David, it was not my intention to suggest that you copied from ZFS.
Sorry to have expressed myself
Hi John,
Yes. There are still AMD CPUs sold without SSSE3. Most notably Athlon.
Instead, Intel is providing SSSE3 from the Core 2 Duo.
A detailed list is available at: http://en.wikipedia.org/wiki/SSSE3
Ciao,
Andrea
On Wed, Nov 20, 2013 at 7:09 PM, John Williams wrote:
> On Wed, Nov 20, 2013 a
); with xmm6 == 7f7f7f7f7f7f...
asm volatile("pand %xmm3,%xmm5"); with xmm3 == 8e8e8e8e8e...
asm volatile("pxor %xmm5,%xmm2");
where xmm2 is the intput/output
Ciao,
Andrea
On Wed, Nov 20, 2013 at 7:43 PM, H. Peter Anvin wrote:
> It is also possible to quickly multiply by
Hi Jim,
I build the matrix in a way that results in coefficients matching
Linux RAID for the first two rows, and at the same time gives
the guarantee that all the square submatrices are not singular,
resulting in a MDS code.
I start forming a Cauchy matrix setting each element to 1/(xi+yj)
where
Hi Peter,
>> static inline uint64_t d2_64(uint64_t v)
>> {
>> uint64_t mask = v & 0x0101010101010101U;
>> mask = (mask << 8) - mask;
>
> (mask << 7) I assume...
No. It's "(mask << 8) - mask". We want to expand the bit at position 0
(in each byte) to the full byte, resulting in 0xFF
Hi Peter,
> Now, that doesn't sound like something that can get neatly meshed into
> the Cauchy matrix scheme, I assume.
You are correct. Multiplication by 2^-1 cannot be used for the Cauchy method.
I used it to implement an alternate triple parity not requiring PSHUFB
that I used as reference fo
Hi,
> First, create a 3 by 6 cauchy matrix, using x_i = 2^-i, and y_i = 0 for i=0,
> and y_i = 2^i for other i.
> In this case: x = { 1, 142, 71, 173, 216, 108 } y = { 0, 2, 4). The
> cauchy matrix is:
>
> 1 2 4 8 16 32
> 244 83 78 183 118 47
> 167 39 213 59 153 82
>
> Divide
Hi Piergiorgio,
> In RAID-6 (as per raid6check) there is an easy way
> to verify where an HDD has incorrect data.
> I suspect, for each 2 parity block it should be
> possible to find 1 error (and if this is true, then
> quad parity is more attractive than triple one).
Yes. The theory say that with
Hi Piergiorgio,
> How about par2? How does this work?
I checked the matrix they use, and sometimes it contains some singular
square submatrix.
It seems that in GF(2^16) these cases are just less common. Maybe they
were just unnoticed.
Anyway, this seems to be an already known problem for PAR2, wi
> Hi Andrea,
>
> On Sat, Nov 23, 2013 at 08:55:08AM +0100, Andrea Mazzoleni wrote:
>> Hi Piergiorgio,
>>
>> > How about par2? How does this work?
>> I checked the matrix they use, and sometimes it contains some singular
>> square submatrix.
>> It seems t
in/end() macros to inlined functions.
- Fixes some more checkpatch.pl warnings.
- Other minor style/comment changes.
Andrea Mazzoleni (2):
lib: raid: New RAID library supporting up to six parities
fs: btrfs: Extends btrfs/raid56 to support up to six parities
fs/btrfs/Kconfig |
() functions are used to handle with
parity instead of the old xor/raid6 ones.
Signed-off-by: Andrea Mazzoleni
---
fs/btrfs/Kconfig | 1 +
fs/btrfs/raid56.c | 278 ++---
fs/btrfs/raid56.h | 12 ++-
fs/btrfs/volumes.c | 4 +-
4 files changed
Hi Neil,
On 01/07, NeilBrown wrote:
> > To do the same with up to six failures, it's now required some kind of sort
> > function.
>
> So I would probably just make sure we always process the block is the "right"
> order. Then sorting would be irrelevant.
> But as I say, I haven't fiddled with th
Hi Chris,
On 01/06, Chris Mason wrote:
> Neat. The faila/failb were always my least favorite part of the btrfs
> code ;) Did you test just raid5/6 or also the higher parity counts?
At this stage no real testing was made with btrfs.
The intention of this btrfs patch is mainly to get feedback on
On 01/06, joystick wrote:
> Just by looking at the Subjects, it seems patch number 0/1 is
> missing. It might have not gotten through to the lists, or be a
> numbering mistake.
The patch files can be also downloaded from:
http://snapraid.sourceforge.net/linux/v2/
Sorry about that,
> Does your co
Hi,
It seems that the patch was to big for some linux lists.
If you miss some patch files, you can download them also at:
http://snapraid.sourceforge.net/linux/v2/
Sorry about that.
Ciao,
Andrea
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To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message t
fs/async_tx/md patches are not SAFE to try as they are not
tested. They are only example code to show how the new raid library could
be integrated in existing code.
Please let me know what do you think. Any kind of feedback is welcome.
Thanks,
Andrea
Andrea Mazzoleni (3):
lib: raid: New RA
ibrary could
be integrated in existing code.
Signed-off-by: Andrea Mazzoleni
---
crypto/async_tx/async_pq.c | 257 +++-
crypto/async_tx/async_raid6_recov.c | 286 +---
drivers/md/Kconfig | 1 +
dri
are now used to handle
all the RAID6 P/Q logic.
For kernel 3.13-rc4.
WARNING! This patch is not tested, and it's NOT meant for inclusion at
this stage. It's only example code to show how the new raid library could
be integrated in existing code.
Signed-off-by: Andrea Mazzoleni
---
tions.
- Fixes some more checkpatch.pl warnings.
- Other minor style/comment changes.
Andrea Mazzoleni (3):
lib: raid: New RAID library supporting up to six parities
fs: btrfs: Extends btrfs/raid56 to support up to six parities
crypto: async_tx: Extends crypto/async_tx to support up to
are now used to handle
all the RAID6 P/Q logic.
For kernel 3.13.
WARNING! This patch is not tested, and it's NOT meant for inclusion at
this stage. It's only example code to show how the new raid library could
be integrated in existing code.
Signed-off-by: Andrea Mazzoleni
---
fs/btr
ibrary could
be integrated in existing code.
Signed-off-by: Andrea Mazzoleni
---
crypto/async_tx/async_pq.c | 257 +++-
crypto/async_tx/async_raid6_recov.c | 286 +---
drivers/md/Kconfig | 1 +
dri
, and updates all the code to use them.
Signed-off-by: Andrea Mazzoleni
---
Makefile| 14 ++-
chunk-recover.c | 18 +---
cmds-balance.c | 20 +++-
cmds-check.c| 7 +-
cmds-chunk.c| 18 +---
cmds-filesystem.c | 12 ++-
ctree.h | 42
Uses alloc_pages_exact() instead of __get_free_pages().
- Removes unnecessary register loads from par1_sse().
- Converts the asm_begin/end() macros to inlined functions.
- Fixes some more checkpatch.pl warnings.
- Other minor style/comment changes.
Andrea Mazzoleni (2):
lib: raid: New RAID
six parities, and updates all the code to use them.
Signed-off-by: Andrea Mazzoleni
---
fs/btrfs/Kconfig | 1 +
fs/btrfs/ctree.h | 50 ++--
fs/btrfs/disk-io.c | 7 +-
fs/btrfs/extent-tree.c | 67 +++
fs/btrfs/inode.c | 3 +-
fs
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