From: NeilBrown <neilb@suse.com>
To: mostafa kishani <mostafa.kishani@gmail.com>, linux-raid@vger.kernel.org
Subject: Re: Implementing Global Parity Codes
Date: Fri, 02 Feb 2018 16:24:18 +1100 [thread overview]
Message-ID: <87d11o2ccd.fsf@notabene.neil.brown.name> (raw)
In-Reply-To: <CACm9mdUJLczo8zSB5UfU9Fd_6VK3+sGCYJYdaEaX0qW1cMLtYA@mail.gmail.com>
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On Sat, Jan 27 2018, mostafa kishani wrote:
> Dear All,
>
> I am going to make some modifications to RAID protocol to make it more
> reliable for my case (for a scientific, and maybe later, industrial
> purpose). For example, I'm going to hold a Global Parity (a parity
> taken across the whole data stripe rather than a row) alongside normal
> row-wise parities, to cope with an extra sector/page failure per
> stripe. Do you have any suggestion how can I implement this with a
> moderate effort (I mean what functions should be modified)? have any
> of you had any similar effort?
In raid5.c the is a "struct stripe_head" which represents a stripe that
is one-page (normally 4K) wide across all devices. All the data for any
parity calculation can all be found in a 'stripe_head'.
You would probably need to modify the stripe_head to represent several
more blocks so that all the Data and Parity for any computation are
always attached to the one stripe_head.
> I also appreciate if you guide me how can I enable DEBUG mode in mdadm.
I assume you mean debug mode on "md".
mdadm is the management tool.
md is the kernel driver.
mdadm doesn't have a debug mode.
md has a number of pr_debug() calls which can each be turned on or off
independently using dynamic debugging
https://www.kernel.org/doc/html/v4.15/admin-guide/dynamic-debug-howto.html
To turn on all pr_debug commands in raid5.c use
echo file raid5.c +p > /sys/kernel/debug/dynamic_debug/control
to turn them off again:
echo file raid5.c -p > /sys/kernel/debug/dynamic_debug/control
NeilBrown
>
> Bests,
> Mostafa
> --
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next prev parent reply other threads:[~2018-02-02 5:24 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-27 5:47 Implementing Global Parity Codes mostafa kishani
2018-01-27 8:37 ` Wols Lists
2018-01-27 14:29 ` mostafa kishani
2018-01-27 15:13 ` Wols Lists
2018-01-28 13:00 ` mostafa kishani
2018-01-29 10:22 ` David Brown
2018-01-29 17:44 ` Wols Lists
2018-01-30 11:47 ` David Brown
2018-01-30 14:18 ` Brad Campbell
2018-01-30 11:30 ` mostafa kishani
2018-01-30 15:14 ` David Brown
2018-01-31 16:03 ` mostafa kishani
2018-01-31 17:53 ` Piergiorgio Sartor
2018-02-02 5:24 ` NeilBrown [this message]
2018-02-03 6:01 ` mostafa kishani
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