Mdadm - Revision history

Leo: Changed quick usage to table format

2023-06-15T17:02:48Z

Changed quick usage to table format

← Older revision		Revision as of 17:02, 15 June 2023
Line 2:		Line 2:

	== Quick Usage ==		== Quick Usage ==
	=~~== Creating a Raid 1 Mirror ===~~		{\| class="wikitable"
	Initialize the disks in your array:{{highlight\|lang=terminal\|code=		!Task
			!Commands
			\|-
			!Initialize disks
			\|Initialize the disks in your array:{{highlight\|lang=terminal\|code=
	# mdadm --zero-superblock /dev/sdb		# mdadm --zero-superblock /dev/sdb
	# mdadm --zero-superblock /dev/sdc		# mdadm --zero-superblock /dev/sdc
	}}		}}
			\|-
	~~Create the array:~~		!Creating a Raid 1 Mirror
			\|
	{{highlight\|lang=terminal\|code=		{{highlight\|lang=terminal\|code=
	# mdadm --create /dev/md0 --chunk=4 --level=1 --raid-devices=2 /dev/sdb /dev/sdc		# mdadm --create /dev/md0 --chunk=4 --level=1 --raid-devices=2 /dev/sdb /dev/sdc
			}}
			\|-
			!Creating a Raid 5
			\|{{highlight\|lang=terminal\|code=
			# mdadm --create /dev/md0 --chunk=128 --level=5 --raid-devices=4 /dev/sdb /dev/sdc /dev/sdd /dev/sde
	}}		}}

	~~That's it! Create the filesystem and you're done.~~		You can specify hot spares with {{code\|1=--spare-devices=N /dev/sdn}}
			\|-
	~~===~~ Saving mdadm config ~~===~~		!Saving mdadm config
	To save your settings, run the following. Note that Ubuntu may have the file under <code>/etc/mdadm/mdadm.conf</code>.		\|To save your settings, run the following. Note that Ubuntu may have the file under <code>/etc/mdadm/mdadm.conf</code>.{{highlight

	{{highlight
	\| lang = terminal		\| lang = terminal
	\| code = # mdadm --detail --scan >> /etc/mdadm.conf		\| code = # mdadm --detail --scan >> /etc/mdadm.conf
Line 28:		Line 36:
	\| lang = terminal		\| lang = terminal
	}}		}}
			\|-
	~~=== Creating a Raid 5 ===~~		!Disassemble / stop an array
	~~Create the array:~~		\|{{highlight\|lang=terminal\|code=
	~~{{highlight~~\|~~lang=terminal\|code=~~
	~~# mdadm --create /dev/md0~~ -~~-chunk=128 --level=5 --raid-devices=4 /dev/sdb /dev/sdc /dev/sdd /dev/sde~~
	}}

	~~You can specify hot spares with {{code\|1=--spare-devices=N /dev/sdn}}~~

	~~===~~ Disassemble / stop an array ~~===~~
	{{highlight\|lang=terminal\|code=
	# mdadm --stop /dev/md0		# mdadm --stop /dev/md0
	}}		}}
			\|-
	~~===~~ Reassemble an array ~~===~~		!Reassemble an array
	{{highlight\|lang=terminal\|code=		\|{{highlight\|lang=terminal\|code=
	# mdadm --assemble --scan		# mdadm --assemble --scan
	}}		}}
Line 51:		Line 51:
	# mdadm --assemble /dev/md0 /dev/sdb /dev/sdc		# mdadm --assemble /dev/md0 /dev/sdb /dev/sdc
	}}		}}
			\|-
	~~===~~ Recovering an Array ~~===~~		!Recovering an Array
	If you want to recover data from an array of a failed system, image the hard drives in case something goes terribly wrong. Then, attempt to reassemble the array with the {{code\|-o}} or {{code\|--readonly}} option for read only. This will prevent mdadm from attempting to resync, recover, or reshape the array.		\|If you want to recover data from an array of a failed system, image the hard drives in case something goes terribly wrong. Then, attempt to reassemble the array with the {{code\|-o}} or {{code\|--readonly}} option for read only. This will prevent mdadm from attempting to resync, recover, or reshape the array.{{highlight\|lang=terminal\|code=

	{{highlight\|lang=terminal\|code=
	# mdadm --readonly --verbose --assemble /dev/md0 /dev/sdb /dev/sdc		# mdadm --readonly --verbose --assemble /dev/md0 /dev/sdb /dev/sdc
	# or		## or
	# mdadm --readonly --verbose --assemble --scan		# mdadm --readonly --verbose --assemble --scan
	}}		}}

	~~Check on the array status:~~

	{{highlight\|lang=terminal\|code=		\|-
			!Check on the array status:
			\|{{highlight\|lang=terminal\|code=
	# cat /proc/mdstat		# cat /proc/mdstat
	}}		}}
			\|}

	== Issues ==		== Issues ==

Leo at 16:57, 15 June 2023

2023-06-15T16:57:19Z

← Older revision		Revision as of 16:57, 15 June 2023
Line 3:		Line 3:
	== Quick Usage ==		== Quick Usage ==
	=== Creating a Raid 1 Mirror ===		=== Creating a Raid 1 Mirror ===
	{{highlight\|lang=terminal\|code=		Initialize the disks in your array:{{highlight\|lang=terminal\|code=
	# mdadm --zero-superblock /dev/sdb		# mdadm --zero-superblock /dev/sdb
	# mdadm --zero-superblock /dev/sdc		# mdadm --zero-superblock /dev/sdc
Line 13:		Line 13:
	}}		}}

	That's it! Create the filesystem and you're done~~. Using 4k chunk size~~.		That's it! Create the filesystem and you're done.

	To save your settings, run:		=== Saving mdadm config ===
			To save your settings, run the following. Note that Ubuntu may have the file under <code>/etc/mdadm/mdadm.conf</code>.

	{{highlight\|lang=terminal\|code=		{{highlight
	~~# echo "DEVICES /dev/sdb /dev/sdc" > /etc/mdadm.conf~~		\| lang = terminal
	# mdadm --detail --scan >> /etc/mdadm.conf		\| code = # mdadm --detail --scan >> /etc/mdadm.conf
	# cat /etc/mdadm.conf		# cat /etc/mdadm.conf
	~~DEVICES /dev/sdb /dev/sdc~~
	ARRAY /dev/md/0 metadata=1.2 name=data:0 UUID=5f486d36:37899fcb:99ad8485:088bc180		ARRAY /dev/md/0 metadata=1.2 name=data:0 UUID=5f486d36:37899fcb:99ad8485:088bc180
			}}The config will also need to be updated in the initrd file. Rebuild the initrd filesystem with:
			{{Highlight
			\| code = # update-initramfs -u
			\| lang = terminal
	}}		}}

Leo: Text replacement - "Category:Linux{{Navbox Linux}}" to "{{Navbox Linux}}Category:Linux"

2019-09-01T06:21:46Z

Text replacement - "Category:Linux{{Navbox Linux}}" to "{{Navbox Linux}}Category:Linux"

← Older revision		Revision as of 06:21, 1 September 2019
Line 113:		Line 113:


	[[Category:Linux]]~~{{Navbox Linux}}~~		{{Navbox Linux}}[[Category:Linux]]
	[[Category:LinuxUtilities]]		[[Category:LinuxUtilities]]

Leo: Text replacement - "{{Navbox Linux}}{{Navbox Linux}}" to "{{Navbox Linux}}"

2019-09-01T05:11:13Z

Text replacement - "{{Navbox Linux}}{{Navbox Linux}}" to "{{Navbox Linux}}"

← Older revision		Revision as of 05:11, 1 September 2019
Line 113:		Line 113:


	[[Category:Linux]]~~{{Navbox Linux}}~~{{Navbox Linux}}		[[Category:Linux]]{{Navbox Linux}}
	[[Category:LinuxUtilities]]		[[Category:LinuxUtilities]]

Leo: Text replacement - "Category:Linux" to "Category:Linux{{Navbox Linux}}"

2019-09-01T05:08:44Z

Text replacement - "Category:Linux" to "Category:Linux{{Navbox Linux}}"

← Older revision		Revision as of 05:08, 1 September 2019
Line 113:		Line 113:


	[[Category:Linux]]{{Navbox Linux}}		[[Category:Linux]]{{Navbox Linux}}{{Navbox Linux}}
	[[Category:LinuxUtilities]]		[[Category:LinuxUtilities]]

Leo: Text replacement - " {{Navbox Linux}}" to ""

2019-09-01T04:55:58Z

Text replacement - " {{Navbox Linux}}" to ""

← Older revision		Revision as of 04:55, 1 September 2019
Line 115:		Line 115:
	[[Category:Linux]]{{Navbox Linux}}		[[Category:Linux]]{{Navbox Linux}}
	[[Category:LinuxUtilities]]		[[Category:LinuxUtilities]]
	~~{{Navbox Linux}}~~

Leo: Text replacement - "Category:Linux " to "Category:Linux{{Navbox Linux}} "

2019-09-01T03:31:37Z

Text replacement - "Category:Linux " to "Category:Linux{{Navbox Linux}} "

← Older revision		Revision as of 03:31, 1 September 2019
Line 113:		Line 113:


	[[Category:Linux]]		[[Category:Linux]]{{Navbox Linux}}
	[[Category:LinuxUtilities]]		[[Category:LinuxUtilities]]
	{{Navbox Linux}}		{{Navbox Linux}}

Leo: /* Issues */

2019-01-01T19:14:44Z

Issues

@@ Line 65: / Line 65: @@
 == Issues ==
 If you're unable to reassemble an array with this error:
 {{highlight|lang=terminal|code=
@@ Line 78: / Line 79: @@
 And then retry reassembling the array again.

Leo at 17:42, 26 April 2017

2017-04-26T17:42:32Z

← Older revision		Revision as of 17:42, 26 April 2017
Line 26:		Line 26:

	=== Creating a Raid 5 ===		=== Creating a Raid 5 ===

	Create the array:		Create the array:
	{{highlight\|lang=terminal\|code=		{{highlight\|lang=terminal\|code=
Line 48:		Line 47:
	# mdadm --assemble /dev/md0 /dev/sdb /dev/sdc		# mdadm --assemble /dev/md0 /dev/sdb /dev/sdc
	}}		}}

			=== Recovering an Array ===
			If you want to recover data from an array of a failed system, image the hard drives in case something goes terribly wrong. Then, attempt to reassemble the array with the {{code\|-o}} or {{code\|--readonly}} option for read only. This will prevent mdadm from attempting to resync, recover, or reshape the array.

			{{highlight\|lang=terminal\|code=
			# mdadm --readonly --verbose --assemble /dev/md0 /dev/sdb /dev/sdc
			# or
			# mdadm --readonly --verbose --assemble --scan
			}}

			Check on the array status:

			{{highlight\|lang=terminal\|code=
			# cat /proc/mdstat
			}}


	== Issues ==		== Issues ==
	If you're unable to reassemble an array with this error:		If you're unable to reassemble an array with this error:
	{{highlight\|lang=terminal\|code=		{{highlight\|lang=terminal\|code=
	# mdadm -A /dev/md0 /dev/sdb /dev/sdc		# mdadm --assemble /dev/md0 /dev/sdb /dev/sdc
	mdadm: cannot open device /dev/sdb: Device or resource busy		mdadm: cannot open device /dev/sdb: Device or resource busy
	mdadm: /dev/sdb has no superblock - assembly aborted		mdadm: /dev/sdb has no superblock - assembly aborted
	}}		}}

	You probably forgot to define your mdadm.conf settings before rebooting and mdadm probably tried to do something with one of your disks to create {{code\|/dev/md127}} (hence the reason the device is busy). To free {{code\|/dev/sdb}} in the above example, just stop {{code\|/dev/md127}} by running:		You probably forgot to define your {{code\|/etc/mdadm.conf}} settings before rebooting and {{code\|mdadm}} probably tried to do something with one of your disks to create {{code\|/dev/md127}} (hence the reason the device is busy). To free {{code\|/dev/sdb}} in the above example, just stop {{code\|/dev/md127}} by running:
	{{highlight\|lang=terminal\|code=		{{highlight\|lang=terminal\|code=
	# mdadm --stop /dev/md127		# mdadm --stop /dev/md127

Leo: formatting

2017-04-26T17:36:25Z

formatting

← Older revision		Revision as of 17:36, 26 April 2017
Line 1:		Line 1:
	~~== Creating~~ a ~~Raid 1 Mirror ==~~		mdadm is a Linux utility to manage software RAID.

	mdadm --zero-superblock /dev/sdb		== Quick Usage ==
	mdadm --zero-superblock /dev/sdc		=== Creating a Raid 1 Mirror ===
			{{highlight\|lang=terminal\|code=
			# mdadm --zero-superblock /dev/sdb
			# mdadm --zero-superblock /dev/sdc
			}}

	Create the array:		Create the array:
	mdadm --create /dev/md0 --chunk=4 --level=1 --raid-devices=2 /dev/sdb /dev/sdc		{{highlight\|lang=terminal\|code=
			# mdadm --create /dev/md0 --chunk=4 --level=1 --raid-devices=2 /dev/sdb /dev/sdc
			}}

	That's it! Create the ~~file system~~ and you're done. Using 4k chunk size.		That's it! Create the filesystem and you're done. Using 4k chunk size.

	To save your settings, run:		To save your settings, run:

	# echo "DEVICES /dev/sdb /dev/sdc" > /etc/mdadm.conf		{{highlight\|lang=terminal\|code=
	# mdadm --detail --scan >> /etc/mdadm.conf		# echo "DEVICES /dev/sdb /dev/sdc" > /etc/mdadm.conf
	# cat /etc/mdadm.conf		# mdadm --detail --scan >> /etc/mdadm.conf
	DEVICES /dev/sdb /dev/sdc		# cat /etc/mdadm.conf
	ARRAY /dev/md/0 metadata=1.2 name=data:0 UUID=5f486d36:37899fcb:99ad8485:088bc180		DEVICES /dev/sdb /dev/sdc
			ARRAY /dev/md/0 metadata=1.2 name=data:0 UUID=5f486d36:37899fcb:99ad8485:088bc180
			}}

	== Creating a Raid 5 ==		=== Creating a Raid 5 ===

	Create the array:		Create the array:
	mdadm --create /dev/md0 --chunk=128 --level=5 --raid-devices=4 /dev/sdb /dev/sdc /dev/sdd /dev/sde		{{highlight\|lang=terminal\|code=
			# mdadm --create /dev/md0 --chunk=128 --level=5 --raid-devices=4 /dev/sdb /dev/sdc /dev/sdd /dev/sde
			}}

	You can specify hot spares with {{code\|--spare-devices=N /dev/sdn}}		You can specify hot spares with {{code\|1=--spare-devices=N /dev/sdn}}

	== Disassemble / stop an array ==		=== Disassemble / stop an array ===
			{{highlight\|lang=terminal\|code=
			# mdadm --stop /dev/md0
			}}

			=== Reassemble an array ===
			{{highlight\|lang=terminal\|code=
			# mdadm --assemble --scan
			}}

	~~mdadm --stop /dev/md0~~		You can assemble an array with specific devices using:
			{{highlight\|lang=terminal\|code=
	~~== Reassemble an array ==~~		# mdadm --assemble /dev/md0 /dev/sdb /dev/sdc
	~~mdadm --assemble --scan~~		}}

	You can assemble an array ~~like~~:
	mdadm --assemble /dev/md0 /dev/sdb /dev/sdc


	== Issues ==		== Issues ==
			If you're unable to reassemble an array with this error:
			{{highlight\|lang=terminal\|code=
			# mdadm -A /dev/md0 /dev/sdb /dev/sdc
			mdadm: cannot open device /dev/sdb: Device or resource busy
			mdadm: /dev/sdb has no superblock - assembly aborted
			}}

	~~# mdadm -A /dev/md0 /dev/sdb /dev/sdc~~		You probably forgot to define your mdadm.conf settings before rebooting and mdadm probably tried to do something with one of your disks to create {{code\|/dev/md127}} (hence the reason the device is busy). To free {{code\|/dev/sdb}} in the above example, just stop {{code\|/dev/md127}} by running:
	~~mdadm: cannot open device /dev/sdb: Device or resource busy~~		{{highlight\|lang=terminal\|code=
	~~mdadm: /dev/sdb has no superblock - assembly aborted~~		# mdadm --stop /dev/md127
			}}
	~~If you~~ forgot to define your mdadm.conf settings and ~~rebooted,~~ mdadm probably tried to do something with one of your disks to create {{code\|/dev/md127}}. To free {{code\|/dev/sdb}} in the above example, just stop {{code\|/dev/md127}} by running:
	mdadm --stop /dev/md127

	And then retry reassembling the array again.		And then retry reassembling the array again.