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--- computing:storage:linux_software_raid [2011/11/27 10:28]
gcooper created
+++ computing:storage:linux_software_raid [2019/10/25 10:42] (current)
gcooper
@@ Line 2: / Line 2: @@
 http://wiki.centos.org/HowTos/SoftwareRAIDonCentOS5
 http://wiki.xtronics.com/index.php/Raid
 http://robbat2.livejournal.com/231207.html
 https://raid.wiki.kernel.org/index.php/Linux_Raid
 http://archive.networknewz.com/2003/0113.html
 Works on block devices, usually partitions.  This is not like strictly-drive-oriented hardware RAID controllers.
-**Show Existing RAID**
+===== Show Existing RAID =====
-mdadm --detail --scan
+<file>
+mdadm --detail --scan --verbose
+</file>
-**Partitioning**
+===== Partitioning =====
-''fdisk /dev/sda''''
+<file>
-''
+fdisk -l /dev/sda
-Using fdisk, create matching partitions on various drives (block devices) of type "fd  Linux raid autodetect" that will be assembled into arrays.
+</file>
-''
-sfdisk -l /dev/sda''''
-Disk /dev/sda'''': 8942 cylinders, 255 heads, 63 sectors/track
+or
+<file>
+sgdisk -p /dev/sda
+</file>
+**Copy Patition Scheme**: https://askubuntu.com/questions/57908/how-can-i-quickly-copy-a-gpt-partition-scheme-from-one-hard-drive-to-another/333923
+:!: Verify ''sfdisk'' recognizes your source partitions.  If not, try ''sgdisk''.
+Using fdisk, create matching partitions on various drives (block devices) of type **fd  Linux raid autodetect** that will be assembled into arrays.
+<file>
+sfdisk -l /dev/sda
+Disk /dev/sda: 8942 cylinders, 255 heads, 63 sectors/track
 Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0
-   Device Boot Start     End   #cyls    #blocks   Id  System
+Device      Boot  Start     End    #cyls    #blocks  Id  System
-/dev/sda1''''   *      0+    242     243-   1951866   fd  Linux raid autodetect
+/dev/sda1   *         0+    242     243-   1951866   fd  Linux raid autodetect
-/dev/sda2''''        243     485     243    1951897+  fd  Linux raid autodetect
+/dev/sda2           243     485     243    1951897+  fd  Linux raid autodetect
-/dev/sda3''''        486     607     122     979965   82  Linux swap
+/dev/sda3           486     607     122     979965   82  Linux swap
+</file>
-''Once you partition the first drive, use sfdisk to duplicate partitions from that first drive to other drives:
+:!: Be careful not to write to the **wrong disk** or you will have a **very bad day**!
-''
-sfdisk -d /dev/sda'''' | sfdisk /dev/sd[b''cd]
-**Create Arrays**
+Once you partition the first drive, use ''sfdisk'' or ''sgdisk'' to replicate partitions from that first drive to other drives:
+<file>
+sfdisk -d /dev/sda | sfdisk /dev/sdb
+</file>
+or
+<file>
+sgdisk /dev/sda -R /dev/sdb
+sgdisk -G /dev/sdb
+</file>
+===== Create Arrays =====
 http://robbat2.livejournal.com/231207.html
 http://en.wikipedia.org/wiki/Mdadm
+<file>
 mdadm --create <[[array]]_device> -c <chunk_size> -l <raid_level> -n <active_disks> -x <spare_disks> <block_devices>
+</file>
-Here is a four-drive RAID5 example where one drive is a hot spare.  Hot spare drives can serve multiple arrays (spare-group).
+Here is a four-drive (partition) RAID5 example where one drive (partition) is a hot spare.  Hot spare drives can serve multiple arrays (spare-group).
+<file>
 mdadm --create /dev/md0 --level=5 --raid-devices=3 --spare-devices=1 --spare-group=groupname /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1
+</file>
-http://www.kernelhardware.org/linux-add-share-hot-spare-device-software-raid/
+===== Add a Drive =====
-**Add a Drive**
+http://www.kernelhardware.org/linux-add-share-hot-spare-device-software-raid/
-mdadm --detail --scan
+<file>
+mdadm --detail --scan --verbose
 mdadm --add /dev/md0 /dev/sdb1
 mdadm --add /dev/md1 /dev/sdb2
 mdadm --add /dev/md2 /dev/sdb3
+</file>
-**Create Conf FIle**
+===== Create Configuration File =====
+Not sure how beneficial or necessary this step is...
+<file>
 mdadm --detail --scan > /etc/mdadm/mdadm.conf
+</file>
-or  (Centos)
+or for Centos:
+<file>
 mdadm --detail --scan --verbose > /etc/mdadm.conf
+</file>
+===== MBR and GRUB =====
+==== MBR ====
+http://www.cyberciti.biz/faq/howto-copy-mbr/
+Assuming you have identical disks with identical partitioning, use this command to copy the entire master boot record (boot code plus partition table) like this, adjusting for your needs:
+<file>
+dd if=/dev/sda of=/dev/sdb bs=512 count=1
+</file>
+==== GRUB ====
+http://wiki.centos.org/HowTos/GrubInstallation
+<file>
+grub
+</file>
+If you have a separate /boot partition:
+<file>
+grub> find /grub/stage1
+</file>
+If you don't:
+<file>
+grub> find /boot/grub/stage1
+</file>
+Then, based on the output of the find command:
+<file>
+grub> root (hd0,0)
+grub> setup (hd2)
+</file>
-Last changed (in Tomboy): 2011-05-02
-Note created (in Tomboy): 2010-12-18

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