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Line 1: − ==Raid: Manual Rebuild== + − {{Warning box|Get it right or you will lose data. Take a backup, let the raid sync}}+ − SME Servers Raid Options are largely automated, if you built your system with a single hard disk, or have a hard disk failure, simply logon as ''admin'' and select ''Disk Redundancy'' to add a new drive to your RAID1 array.+ − But with the best laid plans things don't always goaccording to plan, these are the processes required to do it manually+ − + − + − Line 22:
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Line 44: − + + − mdadm: set /dev/sdb2 faulty in /dev/md2+ + − mdadm: hot removed /dev/sdb2+ + − mdadm: set /dev/sdb1 faulty in /dev/md1+ + − mdadm: hot removed /dev/sdb1 − + Line 85:
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→Do your Disk Maintenance here
{{Level|Advanced}}
{{Level|Advanced}}
{{Warning box|Get it right or you will lose data. '''Take a backup!''' Let the raid sync, this can take quite a while.}}
SME Servers Raid Options are largely automated, if you built your system with a single hard disk simply logon as admin and select Disk Redundancy to add a new drive to your RAID1 array. The same procedure is used if you have a disk failure in a RAID array and you have replaced that failed disk.
But with the best laid plans things don't always go according to plan, these are the processes required to do it manually.
See also: [[Hard Disk Partitioning]] and [[Raid#Resynchronising_a_Failed_RAID]]
== HowTo: Manage/Check a RAID1 Array from the command Line ==
==HowTo: Manage/Check a RAID1 Array from the command Line==
===What is the Status of the Array===
=== What is the Status of the Array ===
[root@ ~]# '''cat /proc/mdstat'''
[root@ ~]# '''cat /proc/mdstat'''
unused devices: <none>
unused devices: <none>
== HowTo: Reinstate a disk from the RAID1 Array with the command Line ==
==HowTo: Reinstate a disk from the RAID1 Array with the command Line==
=== Look at the mdstat ===
===Look at the mdstat===
First we must determine which drive is in default.
First we must determine which drive is in default.
{{note box|As we can see the partition sdb2 is in default, we can see the flag: sdb2 [2] (F). We need to resynchronize the disk sdb to the existing array md2.}}
{{note box|As we can see the partition sdb2 is in default, we can see the flag: sdb2 [2] (F). We need to resynchronize the disk sdb to the existing array md2.}}
=== Fail and remove the disk, '''sdb''' in this case ===
===Fail and remove the disk, '''sdb''' in this case===
mdadm: set /dev/sdb2 faulty in /dev/md2
[root@ ~]# '''mdadm --manage /dev/md2 --fail /dev/sdb2'''
[root@ ~]# '''mdadm --manage /dev/md2 --fail /dev/sdb2'''
mdadm: hot removed /dev/sdb2
[root@ ~]# '''mdadm --manage /dev/md2 --remove /dev/sdb2'''
[root@ ~]# '''mdadm --manage /dev/md2 --remove /dev/sdb2'''
mdadm: set /dev/sdb1 faulty in /dev/md1
[root@ ~]# '''mdadm --manage /dev/md1 --fail /dev/sdb1'''
[root@ ~]# '''mdadm --manage /dev/md1 --fail /dev/sdb1'''
mdadm: hot removed /dev/sdb1
[root@ ~]# '''mdadm --manage /dev/md1 --remove /dev/sdb1'''
[root@ ~]# '''mdadm --manage /dev/md1 --remove /dev/sdb1'''
=== Do your Disk Maintenance here ===
===Do your Disk Maintenance here===
At this point the disk is idle.
At this point the disk is idle.
[root@ ~]# '''smartctl -l selftest /dev/sdb'''
[root@ ~]# '''smartctl -l selftest /dev/sdb'''
{{Note box|if you need to change the disk due to physical failure found by the smartctl command, install a new disk of the same capacity (or more) and enter the following commands to recreate new partitions by copying them from healthy disk sda.}}
You can refer to this page for more information how activate or understand the Analysis and Reporting Technology (SMART) [[Monitor_Disk_Health]]
{{Note box|if you need to change the disk due to physical failure found by the smartctl command, install a new disk of the same capacity (or more) and enter the following commands to recreate new partitions by copying them from healthy disk sda.}}<!-- Do NOT try to use sfdisk on disks llarger than 2 TiB, use gdisk or similar, see below. -->
[root@ ~]# '''sfdisk -d /dev/sda > sfdisk_sda.output'''
[root@ ~]# '''sfdisk -d /dev/sda > sfdisk_sda.output'''
[root@ ~]# '''sfdisk /dev/sdb < sfdisk_sda.output'''
[root@ ~]# '''sfdisk /dev/sdb < sfdisk_sda.output'''
GPT Disks
Larger disks will be GPT Disks, sfdisk will not work - you will need to use gdisk and partx (parted)
[root@ ~]# '''yum install gdisk'''
The copy the partition table from a good disk to the new disk, the first line will copy the partition table from disk sda to sdd, the second will randomize the GUID
[root@ ~]# '''sgdisk /dev/sda -R /dev/sdd'''
[root@ ~]# '''sgdisk -G /dev/sdd'''
To view the partitions use partx
[root@ ~]# '''partx -l /dev/sdd'''
If you want to reinstate the same disk without replacing it, go to the next step.
If you want to reinstate the same disk without replacing it, go to the next step.
=== Add the partitions back ===
===Add the partitions back===
mdadm: hot added /dev/sdb1
[root@ ~]# '''mdadm --manage /dev/md1 --add /dev/sdb1'''
[root@ ~]# '''mdadm --manage /dev/md1 --add /dev/sdb1'''
mdadm: hot added /dev/sdb1
mdadm: hot added /dev/sdb2
[root@ ~]# '''mdadm --manage /dev/md2 --add /dev/sdb2'''
[root@ ~]# '''mdadm --manage /dev/md2 --add /dev/sdb2'''
=== Another Look at the mdstat ===
===Another Look at the mdstat===
[root@sme8-64-dev ~]# cat /proc/mdstat
[root@sme8-64-dev ~]# cat /proc/mdstat
unused devices: <none>
unused devices: <none>
{{note box|with a new disk it may be worthwhile to reinstall grub to avoid problems on startup error. The grub is the program that allows you to launch the operating systems.please enter the following commands. }}
{{note box|with a new disk it may be worthwhile to reinstall grub to avoid problems on startup error. The grub is the program that allows you to launch the operating systems. Please enter the following commands. }}
== HowTo: Write the GRUB boot sector ==
==HowTo: Write the GRUB boot sector==
{{Warning box|as the dd command is named "data destroyer" you need to be extremely prudent and sure of the name of source partition and/or destination. At first you should skip the dd command, Step 1 below, and attempt to install grub without it, see Step 2 below. If grub can be installed without using dd, then Step 1 can be discarded. }}
*1.dd
[root@ ~]# '''dd if=/dev/sda1 of=/dev/sdb1'''
[root@ ~]# '''dd if=/dev/sda1 of=/dev/sdb1'''
*2.grub
[root@ ~]# '''grub'''
[root@ ~]# '''grub'''
Running "embed /grub/e2fs_stage1_5 (hd0)"... 16 sectors are embedded.
Running "embed /grub/e2fs_stage1_5 (hd0)"... 16 sectors are embedded.
succeeded
succeeded
Running "install /grub/stage1 (hd0) (hd0)1+16 p (hd0,0)/grub/stage2 /grub/grub.conf"... succeeded
Running "install /grub/stage1 (hd0) (hd1)1+16 p (hd0,0)/grub/stage2 /grub/grub.conf"... succeeded
Done.
Done.
grub> '''quit'''
grub> '''quit'''
<noinclude>
<noinclude>[[Category:Howto]][[Category:Administration:Storage]]</noinclude>
[[Category:Howto]]
[[Category:Administration:Storage]]
</noinclude>