From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: Implementing Global Parity Codes Date: Fri, 02 Feb 2018 16:24:18 +1100 Message-ID: <87d11o2ccd.fsf@notabene.neil.brown.name> References: Mime-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: mostafa kishani , linux-raid@vger.kernel.org List-Id: linux-raid.ids --=-=-= Content-Type: text/plain 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 > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEG8Yp69OQ2HB7X0l6Oeye3VZigbkFAlpz9gIACgkQOeye3VZi gbm1FA//U1ZJcsGFLhGqWZgeciO6qvBEgsDLwb0hJ2J/Dxiu9Wd2X1woWGsttnuK qWl9IX0EqcUvAwpooTkrJMEqdnA2WvFZN5JIOJ9s4BDTnSW8g9ctTiRb1KOx6lBT Yuv++WL0u5oaZAS1yY7ykvaBJpjqYDFOeo7bu9L40jJb8LzJ0iGdcJY5QUED0SAe 7Rx8Rbw3EwilXQSPpszMuJkj5791rvU+QuDuyTcIVO7TL/qGm8zkW5naFeC+j7rZ KWE49DVvsjypz+BR8MrIJBXdlbx8FkgtIzh0MzJTvcJlqD7BD8+7uRucqXSOIw+w m5lAMVZy20mBAYMfBO+FLKW0lgfrvit9cvu2Jt3agBf0yOe2o56S/vmmvuVIQiVa Otu4Cn2ivzWQo2UZtR8ddc96nEegmLDrdAjHkv20uUPojOi+ePqp2tQRqZOjrlDF tcVeqsMWX/1I5ddALP3kErMxfVrfpZHTgI7tY5kdvGW+FvBFSpfzfNkIwMnuThPP u9dl5L95dl96AwrtFNmxUJZK2wYexywtkimcsA3dMewlH9sj+YVE9xeToiJ6uGBY mZN3FwNlm+k42TBkneYZ+IIRxZkkQ51m7+/yFLoooKf2N3qIpTg6LAxjlikulLTw G+EOvpe5014akJRJtY8Z+Rzp2+6Swh+BaWcZOw5G5Zpvogdt20c= =VINW -----END PGP SIGNATURE----- --=-=-=--