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
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