On Sat, 14 Sep 2013 00:39:20 -0500 Ian Pilcher <arequipeno@xxxxxxxxx> wrote: > I'm in the process of writing a program to monitor various aspects of > my NAS. As part of this effort, I've been simulating RAID disk failures > in a VM, and I noticed something that seems very odd. > > Namely, when a sufficient number of disks has been removed from a RAID-5 > or RAID-6 array to make it inoperable, the array is still shown as > "active" in /proc/mdstat and "clean" in the sysfs array_state file. For > example: > > md0 : active raid5 sde[3](F) sdd[2] sdc[1](F) sdb[0] > 6286848 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/2] [U_U_] > > (mdadm does show the state as "clean, FAILED".) > > Is this the expected behavior? Yes. > > AFAICT, this means that there is no single item in either /proc/mdstat > or sysfs that indicates that an array such as the example above has > failed. My program will have to parse the RAID level, calculated the > number of failed members (if any), and determine whether that RAID level > can survive that number of failures. Is this correct? Yes. > > Anything I'm missing? mdadm already does this for you. "mdadm --detail /dev/md0". NeilBrown > > Thanks! >
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