LINUX: instalar Raid y reemplazar un disco y volver a habilitar.

en google buscar: replace disk mdadm
Primer link
http://www.howtoforge.com/replacing_hard_disks_in_a_raid1_array


Instalacion raid
Despues de instalr el server con raid se verifica el estado de los discos:

[root@localhost ~]# cat /proc/mdstat 
Personalities : [raid1] 
md0 : active raid1 sdb1[1] sda1[0]
      104320 blocks [2/2] [UU]
      
md1 : active raid1 sdb2[1] sda2[0]
      20860288 blocks [2/2] [UU]
      
unused devices:
[root@localhost ~]# 



Maracar el sdb1 como fallido
[root@localhost ~]# mdadm --manage /dev/md0 --fail /dev/sdb1
mdadm: set /dev/sdb1 faulty in /dev/md0

Verificar:
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid1] 
md0 : active raid1 sdb1[2](F) sda1[0]
      104320 blocks [2/1] [U_]
      
md1 : active raid1 sdb2[1] sda2[0]
      20860288 blocks [2/2] [UU]
      
unused devices:
[root@localhost ~]# 

Remover el sdb1 del md0
[root@localhost ~]# mdadm --manage /dev/md0 --remove /dev/sdb1
mdadm: hot removed /dev/sdb1
You have mail in /var/spool/mail/root
[root@localhost ~]# 

Verificar:
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid1] 
md0 : active raid1 sda1[0]
      104320 blocks [2/1] [U_]
      
md1 : active raid1 sdb2[1] sda2[0]
      20860288 blocks [2/2] [UU]
      
unused devices:
[root@localhost ~]# 

Repetir los mismos pasos para sdb2 (marcar como fallido y remover)

Marcar como fallido
[root@localhost ~]# mdadm --manage /dev/md1 --fail /dev/sdb2
mdadm: set /dev/sdb2 faulty in /dev/md1

Verificar:
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid1] 
md0 : active raid1 sda1[0]
      104320 blocks [2/1] [U_]
      
md1 : active raid1 sdb2[2](F) sda2[0]
      20860288 blocks [2/1] [U_]
      
unused devices:
[root@localhost ~]# 

Remover sdb2 de md1
[root@localhost ~]# mdadm --manage /dev/md1 --remove /dev/sdb2
mdadm: hot removed /dev/sdb2

Verificar
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid1] 
md0 : active raid1 sda1[0]
      104320 blocks [2/1] [U_]
      
md1 : active raid1 sda2[0]
      20860288 blocks [2/1] [U_]
      
unused devices:
[root@localhost ~]# 

En este punto se apaga la maquina. Se reemplaza fisicamente el disco y se vuelve a prender la maquina


Agregar el nuevo disco para que el raid lo tome en cuenta:

Lo primero es crear las mismas particiones del disco operativo:

[root@localhost ~]# sfdisk -d /dev/sda | sfdisk /dev/sdb
Checking that no-one is using this disk right now ...
OK


Disk /dev/sdb: 2610 cylinders, 255 heads, 63 sectors/track
Old situation:
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0


   Device Boot Start     End   #cyls    #blocks   Id  System
/dev/sdb1   *      0+     12      13-    104391   fd  Linux raid autodetect
/dev/sdb2         13    2609    2597   20860402+  fd  Linux raid autodetect
/dev/sdb3          0       -       0          0    0  Empty
/dev/sdb4          0       -       0          0    0  Empty
New situation:
Units = sectors of 512 bytes, counting from 0


   Device Boot    Start       End   #sectors  Id  System
/dev/sdb1   *        63    208844     208782  fd  Linux raid autodetect
/dev/sdb2        208845  41929649   41720805  fd  Linux raid autodetect
/dev/sdb3             0         -          0   0  Empty
/dev/sdb4             0         -          0   0  Empty
Successfully wrote the new partition table


Re-reading the partition table ...


If you created or changed a DOS partition, /dev/foo7, say, then use dd(1)
to zero the first 512 bytes:  dd if=/dev/zero of=/dev/foo7 bs=512 count=1
(See fdisk(8).)
You have new mail in /var/spool/mail/root
[root@localhost ~]# 


[root@localhost ~]# fdisk -l


Disk /dev/sda: 21.4 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes


   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          13      104391   fd  Linux raid autodetect
/dev/sda2              14        2610    20860402+  fd  Linux raid autodetect


Disk /dev/sdb: 21.4 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes


   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *           1          13      104391   fd  Linux raid autodetect
/dev/sdb2              14        2610    20860402+  fd  Linux raid autodetect


Disk /dev/md1: 21.3 GB, 21360934912 bytes
2 heads, 4 sectors/track, 5215072 cylinders
Units = cylinders of 8 * 512 = 4096 bytes


Disk /dev/md1 doesn't contain a valid partition table


Disk /dev/md0: 106 MB, 106823680 bytes
2 heads, 4 sectors/track, 26080 cylinders
Units = cylinders of 8 * 512 = 4096 bytes


Disk /dev/md0 doesn't contain a valid partition table
[root@localhost ~]# 


Agregar /dev/sdb1 a /dev/md0 y /dev/sdb2 a /dev/md1
[root@localhost ~]# mdadm --manage /dev/md0 --add /dev/sdb1
mdadm: re-added /dev/sdb1
[root@localhost ~]# 
[root@localhost ~]# mdadm --manage /dev/md1 --add /dev/sdb2 
mdadm: re-added /dev/sdb2
[root@localhost ~]# 

Despues de agregar los discos automaticamente se comienzan a sincronizar. Se puede verificar:
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid1] 
md0 : active raid1 sdb1[1] sda1[0]
      104320 blocks [2/2] [UU]
      
md1 : active raid1 sdb2[2] sda2[0]
      20860288 blocks [2/1] [U_]
      [=>...................]  recovery =  5.2% (1098752/20860288) finish=6.8min speed=47771K/sec
      
unused devices:
[root@localhost ~]#