Removing and Replacing Disks5-14 Express5800/ftServer: System Administrator’s Guide for the Linux Operating SystemN O T EThe device names displayed in /proc/mdstat are thekernel names for each device. These are different fromthe user device names displayed by the mdadmcommand.Example 5-2. Checking the Current State of RAID# cat /proc/mdstatPersonalities : [raid0] [raid1]md30 : active raid0 md21[1] md20[0]286743808 blocks 64k chunksmd21 : active raid1 sdf1[1] sde1[0]143371968 blocks [2/1] [_U]md20 : active raid1 sdd1[1] sdb1[0]143371968 blocks [2/2] [UU]md1 : active raid1 sdc2[1] sda2[0]2096384 blocks [2/2] [UU]md2 : active raid1 sdc3[2](F) sda3[0]31647936 blocks [2/1] [U_]md0 : active raid1 sdc1[1] sda1[0]2096384 blocks [2/2] [UU]unused devices: In this example, md30 is a RAID-0 array made up of md20 and md21. The remainingstanzas are for RAID-1 arrays. Note that md21 is operating in degraded mode. It ismissing a disk: [2/1] [_U].Removing and Replacing DisksFor disk fault tolerance, disk mirrors must be maintained when disks or CPU-I/Oenclosures are removed and replaced. For information about the recommendedpartnering confirmation for internal disks, see ‘‘Configuring Internal Disks’’ on page 5-3.This section discusses the following topics:• ‘‘Disk Insertion”• ‘‘Administering RAID Arrays”
