>>> Is there any way how to tell mdadm explicitly how to set up >>> the pairs of mirrored drives inside a RAID-10 volume? >> If you're using RAID10,n2 (the default layout) then adjacent >> pairs of drives in the create command will be mirrors, [ ... ] I did that once with a pair of MD1000 shelves from Dell and that worked pretty well (except it was very painful to configure the shelves with each disk as separate volume). > half of the disks forming the RAID-10 volume disappeared. > After removing them using mdadm --remove, and adding them > back, iostat reports that they are resynced one disk a time, > not all just-added disks in parallel. That's very interesting news. Thanks for reporting this though, it is something to keep in mind. > [ ... ] Otherwise it would be better for us to discard RAID-10 > altogether, and use several independent RAID-1 volumes joined > together I suspect that that MD runs one recovery per array at a time, and 'raid10' arrays are a single array. Which would be interesting to know in general, for example how many drives would be rebuilt at the same time in a 2-drive failure on a RAID6. You might try a two layer arrangements, as a 'raid0' of 'raid1' pairs, instead of a 'raid10'. The two things with MD are not the same, for example you can do layouts like a 3-drive 'raid10'. > using LVM (which we will probably use on top of the RAID-10 > volume anyway). Oh no! LVM is nowhere as nice as MD for RAIDing and is otherwise largely useless (except regrettably for snapshots) and has some annoying limitations. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
