The xfs filesystem does not support shrinking. This post is mainly about disk replacement and expansion under RAID 10. 1. RAID States and Disk States In mdadm, the RAID states are: clean, normal degraded, still readable and writable, but with reduced fault tolerance reshaping, reorganization in progress, appears during expansion and shrinking resyncing, data synchronization in progress recovering, data recovery in progress, accompanied by degradation as a disk is rebuilt failed In mdadm, the disk states are:

1. Disk Baseline Testing 1.1 4k Random Write 1 2 3 4 5 6 7 8 9 10 11 12 13 14 fio \ --name=4k_randwrite \ --rw=randwrite \ --bs=4k \ --ioengine=libaio \ --direct=1 \ --numjobs=8 \ --iodepth=32 \ --size=20G \ --time_based \ --runtime=120 \ --group_reporting \ --allow_mounted_write=1 \ --filename=/data1/fio-4k-randwrite.dat 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 Starting 8 processes 4k_randwrite: Laying out IO file (1 file / 20480MiB) Jobs: 8 (f=8): [w(8)][100.