On Tue, 03 Apr 2012 15:53:01 +1000 NeilBrown <neilb@xxxxxxx> wrote: > Currently a reshape operation always progresses from the start > of the array to the end unless the number of devices is being > reduced, in which case it progressed in the opposite direction. > > To reverse a partial reshape which changes the number of devices > you can stop the array and re-assemble with the raid-disks numbers > reversed and it will undo. > > However for a reshape that does not change the number of devices > it is not possible to reverse the reshape in the middle - you have to > wait until it completes. > > So add a 'reshape_direction' attribute with is either 'forwards' or > 'backwards' and can be explicitly set when delta_disks is zero. > > This will become more important when we allow the data_offset to > change in a reshape. Then the explicit statement of what direction is > being used will be more useful. > > This can be enabled in raid5 trivially as it already supports > reverse reshape and just needs to use a different trigger to request it. Hello, Is it possible to use this to cancel a RAID5 reshape that is reducing the number of devices? I understand that reshape goes backwards by design in this case, so I need to switch it to "forwards". I stopped the reshaping array and then started it with "mdadm --assemble --freeze-reshape" and listing the backup file and all the devices on the command line. But even then: # echo forwards > /sys/block/md0/md/reshape_direction -bash: echo: write error: Device or resource busy -- With respect, Roman ~~~~~~~~~~~~~~~~~~~~~~~~~~~ "Stallman had a printer, with code he could not see. So he began to tinker, and set the software free."
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