On Wed, Dec 23 2015, George Rapp wrote: > >> The current state of the array is (I think) that it looks like a reshape >> to reduce the number of devices in the array has very nearly completed. >> Only the first stripe needs to be completed. Whether that first stripe >> is still in the old "N+1" device layout or the new "N" device layout is >> unknown to the kernel - this information is only in the backup file >> (which doesn't exist). > > Hmmm. Maybe you're thinking of a different case. This is mine: > http://marc.info/?l=linux-raid&m=143880359028232&w=2 > > My problem was that I was *increasing* the number of devices from 5 to > 6. Also, I don't believe the reshape actually got anywhere, per > /proc/mdstat, which I was watching at the time, because the kernel was > denied write access to my backup file by SELinux. Yes, but then you did "--assemble --update=revert-reshape" didn't you? So now it looks like it is being reduced in size. > I was able to dump the metadata from the six component devices of the > RAID 6 array with: > > # mdadm --dump=/home/gwr/c/dev-md4-mdadm-dump /dev/sdj1 > /dev/sdj1 saved as /home/gwr/c/dev-md4-mdadm-dump/sdj1. > /dev/sdj1 also saved as > /home/gwr/c/dev-md4-mdadm-dump/wwn-0x5000cca222d7b996-part1. > /dev/sdj1 also saved as > /home/gwr/c/dev-md4-mdadm-dump/wwn-0x13372914453769768960x-part1. > /dev/sdj1 also saved as > /home/gwr/c/dev-md4-mdadm-dump/ata-Hitachi_HUA722020ALA331_B9HP5Y2F-part1. Oh, that's right - you give component device names to --dump, not the array. Sorry. > > but after doing that, I have a whole bunch of huge (presumabily > sparse) files in my output directory: > > [root@backend3 dev-md4-mdadm-dump]# ll > total 192 > -rw-r--r-- 4 root root 1964963324416 Dec 22 20:42 > ata-Hitachi_HUA722020ALA331_B8HGR23Z-part1 ... > -rw-r--r-- 4 root root 1964963324416 Dec 22 20:42 > wwn-0x6368721060505866240x-part1 > -rw-r--r-- 4 root root 1964968599552 Dec 22 20:42 > wwn-0x7703416737422790657x-part4 > > and "tar -c -v -z -f dev-md4-mdadm-dump.tar.gz dev-md4-mdadm-dump/" > didn't produce a tiny file, but a huge one (15MB and growing in just > 10 minutes), so I killed it. > > Any further thoughts about how to proceed? Thanks for your help. Maybe add "-S" option to tar. I don't do this often enough to remember the details. I though tar auto-detected sparse files, but apparently not. NeilBrown
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