which two disks can I remove from RAID 10 without breaking the array?
near-copies means that there is raid like this?
raid0(raid1(sdaX, sdbX), raid1(sdcX, sddX))
= sdb and sdd can be removed
cat /proc/mdstat
Personalities : [raid1] [raid10]
md2 : active raid10 sda3[0] sdd3[3] sdc3[2] sdb3[1]
19550976 blocks 64K chunks 2 near-copies [4/4] [UUUU]
md1 : active (auto-read-only) raid10 sdc2[0] sdd2[3] sda2[2] sdb2[1]
7823488 blocks 64K chunks 2 near-copies [4/4] [UUUU]