Vyměníte disk v raid 6 a najednou vidíte tohle:

cat /proc/mdstat
Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10]
md1 : inactive sdf14 sdd12 sdh16 sde13 sdc11
19534428160 blocks super 1.2

md0 : active raid1 sdg1[1] sda1[0]
488253440 blocks super 1.2 [2/2] [UU]
bitmap: 2/4 pages [8KB], 65536KB chunk

mdadm --detail /dev/md1
/dev/md1:
Version : 1.2
Raid Level : raid0
Total Devices : 5
Persistence : Superblock is persistent

      State : inactive

       Name : machine:1  (local to host machine)
       UUID : 9ee08fc6:7789a8cf:bc9206e8:3497055a
     Events : 155222

Number   Major   Minor   RaidDevice

   -       8      113        -        /dev/sdh1
   -       8       81        -        /dev/sdf1
   -       8       65        -        /dev/sde1
   -       8       49        -        /dev/sdd1
   -       8       33        -        /dev/sdc1

Připravíme nově vložený disk do RAIDu

nově vložený disk je pomocí fdisk -l disk /dev/sdb

parted /dev/sdb

(parted) unit TB
(parted) mkpart primary 0.00TB 4.00TB
(parted) print
Model: ATA HGST HUS726040AL (scsi)
Disk /dev/sdb: 4.00TB
Sector size (logical/physical): 512B/4096B
Partition Table: gpt
Disk Flags:

Number Start End Size File system Name Flags
1 0.00TB 4.00TB 4.00TB primary

(parted) set 1 raid on
(parted) print
Model: ATA HGST HUS726040AL (scsi)
Disk /dev/sdb: 4.00TB
Sector size (logical/physical): 512B/4096B
Partition Table: gpt
Disk Flags:

Number Start End Size File system Name Flags
1 0.00TB 4.00TB 4.00TB primary raid

(parted) quit
Information: You may need to update /etc/fstab.

Zastavíme a znovu pustíme raid

mdadm –stop /dev/md1
mdadm: stopped /dev/md1
# mdadm -A –force /dev/md1
mdadm: /dev/md1 has been started with 5 drives (out of 6).
# mdadm –add /dev/md1 /dev/sdb1
mdadm: added /dev/sdb1
# mdadm –detail /dev/md1

mdadm –detail /dev/md1
/dev/md1:
Version : 1.2
Creation Time : Fri Aug 10 17:26:02 2018
Raid Level : raid6
Array Size : 15627542528 (14903.59 GiB 16002.60 GB)
Used Dev Size : 3906885632 (3725.90 GiB 4000.65 GB)
Raid Devices : 6
Total Devices : 6
Persistence : Superblock is persistent

Intent Bitmap : Internal

Update Time : Sat Feb 18 02:04:55 2023
      State : clean, degraded, recovering

Active Devices : 5
Working Devices : 6
Failed Devices : 0
Spare Devices : 1

     Layout : left-symmetric
 Chunk Size : 512K

Rebuild Status : 0% complete

       Name : machine:1  (local to host machine)
       UUID : 9ee08fc6:7789a8cf:bc9206e8:3497055a
     Events : 155225

Number   Major   Minor   RaidDevice State
   7       8       17        0      spare rebuilding   /dev/sdb1
   1       8       33        1      active sync   /dev/sdc1
   2       8       49        2      active sync   /dev/sdd1
   3       8       65        3      active sync   /dev/sde1
   4       8       81        4      active sync   /dev/sdf1
   6       8      113        5      active sync   /dev/sdh1

A už běží resynchronizace:

cat /proc/mdstat
Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10]
md1 : active raid6 sdb1[7] sdc1[1] sdh1[6] sdf1[4] sde1[3] sdd1[2]
15627542528 blocks super 1.2 level 6, 512k chunk, algorithm 2 [6/5] [_UUUUU]
[>………………..] recovery = 0.1% (5616952/3906885632) finish=939.8min speed=69179K/sec
bitmap: 0/30 pages [0KB], 65536KB chunk

Upozornění: Nezodpovídám za ztrátu vašich dat, ani za tento návod. Jen jsem sem vložil postup, který fungoval v mém případě a v mé situaci. Vaše situace může být odlišná a proto vám nemusí řešení vyhovovat.