how to replace disk 2 or 1 in raid 1

Discussion in 'HOWTO-Related Questions' started by GioMBG, Aug 8, 2011.

  1. GioMBG

    GioMBG New Member

    Ciao HowToForge Staff,
    I am a raid1 newbie,
    I read all the guides I've found about but I still can not understand the first things to do in my situation with 3 disk in Hetzner...
    the first 2 disk are in raid1 (I think) before to install all the server I strictly need to make a test as (for example) degarde a disk and simulate the replace and rebuild the array
    there are any problem to make experiments the server is all to configure
    Code:
    [[email protected] ~]# fdisk -l
    
    Disco /dev/sda: 1500.3 GB, 1500301910016 byte
    
    255 testine, 63 settori/tracce, 182401 cilindri
    Unità = cilindri di 16065 * 512 = 8225280 byte
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Identificativo disco: 0x0008f32d
    
    Dispositivo Boot      Start         End      Blocks   Id  System
    /dev/sda1               1         262     2102562   fd  Autorilevamento raid di Linux
    /dev/sda2             263         295      265072+  fd  Autorilevamento raid di Linux
    /dev/sda3             296      182401  1462766445   fd  Autorilevamento raid di Linux
    
    Disco /dev/sdc: 1500.3 GB, 1500301910016 byte
    
    255 testine, 63 settori/tracce, 182401 cilindri
    Unità = cilindri di 16065 * 512 = 8225280 byte
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Identificativo disco: 0x00064a51
    
    Dispositivo Boot      Start         End      Blocks   Id  System
    /dev/sdc1               1      182401  1465136001   83  Linux
    
    Disco /dev/sdb: 1500.3 GB, 1500301910016 byte
    
    255 testine, 63 settori/tracce, 182401 cilindri
    Unità = cilindri di 16065 * 512 = 8225280 byte
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Identificativo disco: 0x00058c00
    
    Dispositivo Boot      Start         End      Blocks   Id  System
    /dev/sdb1               1         262     2102562   fd  Autorilevamento raid di Linux
    /dev/sdb2             263         295      265072+  fd  Autorilevamento raid di Linux
    /dev/sdb3             296      182401  1462766445   fd  Autorilevamento raid di Linux
    
    Disco /dev/md0: 2152 MB, 2152923136 byte
    2 testine, 4 settori/tracce, 525616 cilindri
    Unità = cilindri di 8 * 512 = 4096 byte
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Identificativo disco: 0x00000000
    
    Il disco /dev/md0 non contiene una tabella delle partizioni valida
    
    Disco /dev/md1: 271 MB, 271319040 byte
    2 testine, 4 settori/tracce, 66240 cilindri
    Unità = cilindri di 8 * 512 = 4096 byte
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Identificativo disco: 0x00000000
    
    Il disco /dev/md1 non contiene una tabella delle partizioni valida
    
    Disco /dev/md2: 1497.9 GB, 1497872728064 byte
    
    2 testine, 4 settori/tracce, 365691584 cilindri
    Unità = cilindri di 8 * 512 = 4096 byte
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Identificativo disco: 0x00000000
    
    Il disco /dev/md2 non contiene una tabella delle partizioni valida
    [[email protected] ~]# 
    
    Code:
    [[email protected] ~]# df -h
    Filesystem            Size  Used Avail Use% Montato su
    /dev/md2              1,4T  809M  1,3T   1% /
    /dev/md1              251M   40M  198M  17% /boot
    
    Code:
    [[email protected] ~]# cat /proc/mdstat
    Personalities : [raid1] 
    md2 : active raid1 sda3[0] sdb3[1]
          1462766336 blocks [2/2] [UU]
          
    md1 : active raid1 sda2[0] sdb2[1]
          264960 blocks [2/2] [UU]
          
    md0 : active raid1 sda1[0] sdb1[1]
          2102464 blocks [2/2] [UU]
          
    unused devices: <none>
    thx
    GioMBG
     
  2. falko

    falko Super Moderator ISPConfig Developer

  3. GioMBG

    GioMBG New Member

    Recovering... SO: You are the number one!

    Hi Falko!
    BIG respect to You and HowToForge!
    was 10 days that I search exactly what You show me now!
    recovering...
    Code:
    [[email protected] ~]# cat /proc/mdstat
    Personalities : [raid1] 
    md2 : active raid1 sdb3[2] sda3[0]
          1462766336 blocks [2/1] [U_]
          [>....................]  recovery =  0.3% (5676736/1462766336) finish=477.4min speed=50865K/sec
          
    md1 : active raid1 sdb2[1] sda2[0]
          264960 blocks [2/2] [UU]
          
    md0 : active raid1 sdb1[1] sda1[0]
          2102464 blocks [2/2] [UU]
          
    unused devices: <none>
    the only think that I've don't understand is here:
    exactly where we read the degraded status?
    really thanks
    really respect
    GioMBG
     
  4. falko

    falko Super Moderator ISPConfig Developer

    [U_] or [_U] means you have a degraded array while [UU] means that everything is ok.
     
  5. GioMBG

    GioMBG New Member

    thanks

    Thanks Falko!
    ciao
    GioMBG
     
  6. preis4u2

    preis4u2 New Member

    Failed Raid-1

    My system was originally setup with two identical Segate 1TB drives and partition as follow:
    /dev/md0 /boot Raid-1
    /dev/md2/ / Raid-1
    /dev/md3/ /var/data Raid-1
    Here is the output from the mdstat command that I ran from bootable BT4 CD as I was not able to boot the actual system that was configured as a Raid-1:
    # cat /proc/mdstat
    Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] [multipath]
    md3 : active raid1 sdb2[1]
    870040128 blocks [2/1] [_U]

    md2 : active raid1 sdb3[1]
    102398208 blocks [2/1] [_U]
    md0 : active raid1 sda1[0]
    104320 blocks [2/1] [U_]
    unused devices: <none>

    Does this mean that both drives have failed? At this point, I do not care if I rebuild or fix the Raid-1 but at least I would like to recover my data that is stored on md3. How do I proceed? Any help will be greatly appreciated. Thank you.

    Kris
     
  7. falko

    falko Super Moderator ISPConfig Developer

    /dev/sda2, /dev/sda3, and /dev/sdb1 have failed. Can you try to rebuild the arrays as follows?

    Code:
    mdadm --manage /dev/md0 --fail /dev/sdb1
    mdadm --manage /dev/md2 --fail /dev/sda3
    mdadm --manage /dev/md3 --fail /dev/sda2
    
    mdadm --manage /dev/md0 --remove /dev/sdb1
    mdadm --manage /dev/md2 --remove /dev/sda3
    mdadm --manage /dev/md3 --remove /dev/sda2
    
    mdadm --zero-superblock /dev/sdb1
    mdadm --zero-superblock /dev/sda3
    mdadm --zero-superblock /dev/sda2
    
    mdadm -a /dev/md0 /dev/sdb1
    mdadm -a /dev/md2 /dev/sda3
    mdadm -a /dev/md3 /dev/sda2
     
  8. GioMBG

    GioMBG New Member

    delete /dev/md0 on /dev/sdc

    I see these 3 not valid partitions on /dev/sdc

    Code:
    [[email protected] mail]# fdisk -l | grep /dev/sdc
    Il disco /dev/md0 non contiene una tabella delle partizioni valida
    Il disco /dev/md1 non contiene una tabella delle partizioni valida
    Il disco /dev/md2 non contiene una tabella delle partizioni valida
    Disco /dev/sdc: 1500.3 GB, 1500301910016 byte
    /dev/sdc1               1      182401  1465136001   83  Linux
    I can delete?
    (this is the 3th hard disk for backup and is not used now for raid)
    Code:
    mdadm --fail /dev/md0 /dev/sdc
    mdadm --remove /dev/md0 /dev/sdc
    thx
    GioMBG
     
    Last edited: Aug 15, 2011
  9. Mark_NL

    Mark_NL New Member

    If i'm not mistaken:

    Don't forget to install grub on the MBR of the new disc if you replaced sda!

    Code:
    grub-install --no-floppy --recheck /dev/sda
    If you have your bios setup to boot from the first disc only, and you replace it with a new one, you must install grub on it's MBR since the MBR is outside of the scope of the md devices
     
  10. preis4u2

    preis4u2 New Member

    Thanks Falko. I will try to rebuild my array today in accordance with your recommendation. I will let how I made out.
     

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