On 2011-03-18 03:29, NeilBrown wrote: > On Tue, 15 Mar 2011 12:45:19 +0100 Michael Gebetsroither <mich...@mgeb.org>
Hi Neil, first, thx for your explanation and answer to my bugreport! >> Package: mdadm >> Version: 2.6.7.2-3 >> Severity: grave >> Justification: causes non-serious data loss >> >> Hi, >> >> mdadm --grow /dev/mdX --size=max shreded the second raid1 array here. >> >> Commands where as following: >> lvextend -L +10G vda/opt >> lvextend -L +10G vdb/opt > > md was not made aware of these changes to the sizes of the individual devices, > so But how should i tell mdadm about the changes? mdadm --grow /dev/md2 --size=max Seems like the logical choice to update the size. >From manpage about -z, --size=: "... This value can be set with --grow for RAID level 1/4/5/6. If the array was created with a size smaller than the currently active drives, the extra space can be accessed using --grow. The size can be given as max which means to choose the largest size that fits on all current drives." This reads exactly like i was using the command (to grow the raid to the maximum size of the individual drives). And it imho nowhere states that you are going to "destroy" your md metadata. >> mdadm --grow /dev/md2 --size=max > > This caused mdadm to do nothing as it always "knew" that all of the available > space on the devices was already in use. Afaik the md raid running (md2) knew that it was still using the old size of the disks (i looked at /sys/block/ for it). Shouldn't mdadm always read the metadata using the size of the running raid-device and not from the individual devices (at least as long as the raid is running)? But yea i see the problem, that the running raid array doesn't have to be the same as described in the metadata. >> After mdadm --stop /dev/md2 the array couldn't be reassambled. >> >> To fix this problem i simply recreated the array with: >> # mdadm --create --assume-clean /dev/md2 -l1 -n2 /dev/vda/opt /dev/vdb/opt >> mdadm: /dev/vda/opt appears to contain an ext2fs file system >> size=10485696K mtime=Tue Feb 22 12:28:24 2011 >> mdadm: /dev/vdb/opt appears to contain an ext2fs file system >> size=10485696K mtime=Tue Feb 22 12:28:24 2011 >> Continue creating array? yes >> mdadm: array /dev/md2 started. > > Excellent! but what to do on e.g raid5 devices? > What this is really a 'wishlist' issue. > You would like mdadm to notice that the devices have changed size, and tell > md, or maybe would like md to be able to be told immediately when it happens. > Or something like that. yea, `mdadm --grow /dev/md2 --size=max` growing the array to the real size of the underlying devices would be nice. michael -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
