Dear Neil, Sincere thanks for the useful information. I really appreciate your help. Bests, Mostafa On Fri, Feb 2, 2018 at 8:54 AM, NeilBrown <neilb@xxxxxxxx> wrote: > 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@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
