Misono, Tomohiro posted on Wed, 11 Oct 2017 11:18:50 +0900 as excerpted: > Add 'btrfs remove missing-all' to remove all the missing devices at once > for improving usability. > > Example: > sudo mkfs.btrfs -f -d raid1 /dev/sdb1 /dev/sdb2 /dev/sdb3 /dev/sdb4 > sudo wipefs -a /dev/sdb1 /dev/sdb3 > sudo mount -o degraded /dev/sdb2 /mnt > sudo btrfs filesystem show /mnt > sudo btrfs device remove missing-all /mnt > sudo btrfs filesystem show /mnt
There's a reason remove missing-all hasn't yet been implemented. Note that the above would be very unlikely to work once a filesystem has been used in any significant way, because raid1 and raid10 are explicitly chunk pairs, *NOT* duplicated N times across N devices. So with two devices missing, chances are that both copies of some chunks will be missing as well, so the filesystem would no longer be mountable degraded- writable, only degraded-readonly, in which case device remove won't work at all because the filesystem is readonly. In fact, until the recent per-chunk check patches went in, it was impossible to mount-writable a raid1 missing two devices at all, because the safeguards simply assumed some chunks would be entirely missing. The only case in which more than a single device missing is likely to be mountable degraded-writable (so device remove will work at all) is raid6, tho with recent patches there's narrow cases in which it /might/ be doable with raid1 as well. Now you may still wish to implement remove missing-all for raid6 mode and for the unusual corner-case raid1/raid10 in which it might work, but the documentation should be pretty clear that save for raid6 it can't be expected to work in most cases. Given that, I think remove missing-all hasn't been implemented as it simply hasn't been considered to be worth the bother for the narrow use- cases in which it will actually work. -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
