LVM - Revision history

Leo: /* Expanding an existing volume */

2022-02-19T00:22:42Z

Expanding an existing volume

← Older revision		Revision as of 00:22, 19 February 2022
Line 174:		Line 174:

	===Expanding an existing volume===		===Expanding an existing volume===
	~~Here's~~ a ~~quick guide on expanding~~ a ~~virtual disk that is using LVM.~~		You can expand a volume by running the following set of commands (or use it as a script):
			{{Highlight
			\| code = #!/bin/bash

	#~~Expand the virtual disk~~		## Assuming partition 3 in /dev/vda contains the LVM volume group
	#~~The OS might not be aware of the disk size change until a reboot. Reboot if the size is still incorrect.~~		/usr/bin/growpart /dev/vda 3
	~~#Resize~~ the ~~partition that~~ LVM ~~is using using {{code\|fdisk}}.~~		/usr/sbin/pvresize -y -q /dev/vda3
	~~##Delete the partition~~		/usr/sbin/lvresize -y -q -r -l +100%FREE /dev/mapper/*root
	~~##Recreate the partition with the same starting location but with a larger size~~		/usr/sbin/xfs_growfs /
	~~##Run {{code\|partprobe}} to update the partition size~~		\| lang = bash
	~~#Resize the LVM physical volume with {{code\|~~pvresize /dev/~~sda1}}~~		}}
	~~#{{code\|pvscan}} should show the LVM having free space~~		In more detail, expanding a LVM volume requires the following steps (replace sda1 with your actual device):
	~~#Resize the LV. Eg: Add 1GB with {{code\|~~lvresize -L +1G /dev/~~centos~~/root}}
	~~#Resize~~ the ~~filesystem.~~

	~~An example from a~~ virtual ~~machine where~~ the disk ~~was expanded from 20GB~~ to ~~40GB~~.		#Expand the virtual disk and verify that the OS sees the disk being grown by running <code>lsblk</code>. If the OS isn't aware of the disk's updated size, reboot the system.
			#Resize the partition using <code>growpart</code> and specify both the device and partition number. Eg: <code>growpart /dev/sda 1</code>. You can alternatively use fdisk to delete and re-create the partition if you don't have growpart, but this is less convenient.
			#Resize the LVM physical volume with <code>pvresize /dev/sda1</code>. Confirm the resize by checking the available free space with <code>pvscan</code>.
			#Resize the logical volume with <code>lvresize</code>. Eg: Add 1GB with <code>lvresize -L +1G /dev/mapper/root</code>, or expand to the full size with <code>lvresize -L +100%FREE /dev/mapper/root</code>
			#Resize the underlying filesystem using <code>xfs_growfs</code> (XFS), <code>resize2fs</code> (EXT), or some other utility appropriate for you filesystem.

			Here's an example run-through on me expanding a virtual disk on a VM:
	{{highlight\|lang=terminal\|code=		{{highlight\|lang=terminal\|code=
	## Expand the partition {{code\|/dev/sda2}} using {{code\|fdisk}}. Then do the following.		## Expand the partition {{code\|/dev/sda2}} using {{code\|fdisk}}. Then do the following.

Leo at 00:37, 2 January 2022

2022-01-02T00:37:28Z

← Older revision		Revision as of 00:37, 2 January 2022
Line 49:		Line 49:
	!Command		!Command
	\|-		\|-
	\|XFS Filesystem		\|[[XFS\|XFS Filesystem]]
	\|<code>xfs_growfs /</code>		\|<code>xfs_growfs /</code>
	\|-		\|-

Leo: size down lv

2022-01-01T23:30:03Z

size down lv

@@ Line 243: / Line 243: @@
 | code = ## If using ext4, use resize2fs
 # resize2fs /dev/mapper/vg-lv
 | lang = terminal
 }}

Leo: /* Snapshot */

2021-11-17T20:53:15Z

Snapshot

← Older revision		Revision as of 20:53, 17 November 2021
Line 123:		Line 123:

	===Using snapshots===		===Using snapshots===
	A snapshot creates a point-in-time copy of a volume. Unlike ZFS, a LVM snapshot creates a separate volume which appears as a separate block device which needs to be mounted separately. There is no need to worry about creating an unclean filesystem ~~with the~~ snapshot because LVM will make the necessary system calls and ~~work so that~~ the filesystem ~~is synced~~ and ~~checkpointed so that~~ the snapshot copy is consistent and clean.		A snapshot creates a point-in-time copy of a volume. Unlike ZFS, a LVM snapshot creates a separate volume which appears as a separate block device which needs to be mounted separately. There is no need to worry about accidentally creating an unclean filesystem when creating a snapshot on a busy filesystem because LVM will make the necessary system calls during the snapshot process to sync and checkpoint the filesystem and ensure the snapshot copy is consistent and clean.

	====Creating, listing, and deleting snapshots====		====Creating, listing, and deleting snapshots====

Leo: /* LVM warns with "open failed: No medium found" */

2021-06-01T22:08:33Z

LVM warns with "open failed: No medium found"

← Older revision		Revision as of 22:08, 1 June 2021
Line 246:		Line 246:
	}}		}}

	== Troubleshooting ==		==Troubleshooting==

	=== LVM warns with "open failed: No medium found" ===		===LVM warns with "open failed: No medium found"===
	When running any LVM related commands, you may get the following warning messages complaining about "No medium found":		When running any LVM related commands, you may get the following warning messages complaining about "No medium found":
	{{Highlight		{{Highlight
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	\| lang = terminal		\| lang = terminal
	}}		}}
	As a workaround, you may configure LVM commands from scanning these devices by adding a filter:		As a workaround, you may configure LVM commands from scanning these devices by adding a filter to <code>/etc/lvm/lvm.conf</code> to reject (<code>r</code>) the iDRAC devices.
	{{Highlight		{{Highlight
	\| code = filter = [ "r{{!}}/dev/disk/by-id/usb-iDRAC.*{{!}}" ]		\| code = filter = [ "r{{!}}/dev/disk/by-id/usb-iDRAC.*{{!}}" ]

Leo at 22:07, 1 June 2021

2021-06-01T22:07:34Z

@@ Line 210: / Line 210: @@
 }}
-==== XFS ====
+====XFS====
 For XFS filesystems, after expanding the volume, resize the filesystem with <code>xfs_growfs</code>:
 {{Highlight
@@ Line 238: / Line 238: @@
 }}
-==== EXT2, EXT3, EXT4 ====
+====EXT2, EXT3, EXT4====
 For the EXT type filesystems, use <code>resize2fs</code> to expand the filesystem.
 {{Highlight
 | code = ## If using ext4, use resize2fs
 # resize2fs /dev/mapper/vg-lv
 | lang = terminal
 }}

Leo: Breaking out filesystem expansions

2021-04-22T23:11:12Z

Breaking out filesystem expansions

← Older revision		Revision as of 23:11, 22 April 2021
Line 5:		Line 5:
	*Ability for a volume to span multiple disks		*Ability for a volume to span multiple disks

	==~~Cheet~~ Sheet==		==Cheat Sheet==
	{\| class="wikitable"		{\| class="wikitable"
	!Action		!Action
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	\|Remove a logical volume		\|Remove a logical volume
	\|<code>lvremove lv_name</code>		\|<code>lvremove lv_name</code>
			\|}
			Not strictly LVM, but after resizing a volume, you will need to resize the filesystem with these commands:
			{\| class="wikitable"
			!Action
			!Command
			\|-
			\|XFS Filesystem
			\|<code>xfs_growfs /</code>
			\|-
			\|EXT2/3/4
			\|<code>resize2fs /dev/vg_name/lv_name</code>
	\|}		\|}

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	}}		}}

	==== Mounting and unmounting a volume ====		====Mounting and unmounting a volume====
	LVM volumes are exposed as a block device. You will need to format a filesystem of your choice and then mount it like any other device.		LVM volumes are exposed as a block device. You will need to format a filesystem of your choice and then mount it like any other device.

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	You may also configure LVM to automatically extend snapshot volumes by editing <code>/etc/lvm/lvm.conf</code> and setting the <code>snapshot_autoextend_threshold</code> value.		You may also configure LVM to automatically extend snapshot volumes by editing <code>/etc/lvm/lvm.conf</code> and setting the <code>snapshot_autoextend_threshold</code> value.

	== Tasks ==		==Tasks==

	===Recovering lost volumes===		===Recovering lost volumes===
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	*http://thecususergroup.proboards.com/thread/4156/recover-thecus-raid-pc		*http://thecususergroup.proboards.com/thread/4156/recover-thecus-raid-pc

	=== Expanding an existing volume ===		===Expanding an existing volume===
	Here's a quick guide on expanding a virtual disk that is using LVM.		Here's a quick guide on expanding a virtual disk that is using LVM.

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	root centos -wi-ao---- <18.00g		root centos -wi-ao---- <18.00g
	swap centos -wi-ao---- 2.00g		swap centos -wi-ao---- 2.00g
			}}
	## Expand your filesystems. If using XFS:
			==== XFS ====
			For XFS filesystems, after expanding the volume, resize the filesystem with <code>xfs_growfs</code>:
			{{Highlight
			\| code = ## Expand your filesystems. If using XFS:
	# xfs_growfs /		# xfs_growfs /
	meta-data=/dev/mapper/centos-root isize=512 agcount=4, agsize=1113856 blks		meta-data=/dev/mapper/centos-root isize=512 agcount=4, agsize=1113856 blks
Line 220:		Line 235:
	= sectsz=512 sunit=0 blks, lazy-count=1		= sectsz=512 sunit=0 blks, lazy-count=1
	realtime =none extsz=4096 blocks=0, rtextents=0		realtime =none extsz=4096 blocks=0, rtextents=0
			\| lang = terminal
			}}

	## If using ext4, use resize2fs		==== EXT2, EXT3, EXT4 ====
			For the EXT type filesystems, use <code>resize2fs</code> to expand the filesystem.
			{{Highlight
			\| code = ## If using ext4, use resize2fs
	# resize2fs /dev/mapper/vg-lv		# resize2fs /dev/mapper/vg-lv
			\| lang = terminal
	}}		}}


	==See Also==		==See Also==

Leo: reorganized content and sections

2021-04-22T22:16:35Z

reorganized content and sections

← Older revision		Revision as of 22:16, 22 April 2021
Line 9:		Line 9:
	!Action		!Action
	!Command		!Command
			\|-
			\|Show physical volume groups (Eg. disks)
			\|<code>pvs</code>
	\|-		\|-
	\|Show volume groups		\|Show volume groups
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	\|}		\|}

	==~~Introduction~~==		==Using LVM==
	[[File:LVM Overview.svg\|alt=Logical Volume Manager, showing disks to physical extents to volume groups to logical volumes\|thumb\|Logical Volume Manager, showing disks to physical extents to volume groups to logical volumes]]		[[File:LVM Overview.svg\|alt=Logical Volume Manager, showing disks to physical extents to volume groups to logical volumes\|thumb\|Logical Volume Manager, showing disks to physical extents to volume groups to logical volumes]]
	LVM allows the creation of volumes which functionally is similar to partitions. This is done by allocating storage into a volume group (VG) which can then be broken up into separate logical volumes (LV).		LVM allows the creation of volumes which functionally is similar to partitions. This is done by allocating storage into a volume group (VG) which can then be broken up into separate logical volumes (LV).

	Unlike a traditional partition scheme, LVM breaks down the backing storage into many small chunks called physical extents (PE) which are typically 4MB in size. These physical extents are assigned to their respective logical volumes (referred to as Logical Extents) and can be added or removed after creation allowing for volumes to grow or shrink as needed. One of the added benefits with this design allows for the ability to implement copy-on-write (COW) allowing for quick and space-efficient snapshotting.		Unlike a traditional partition scheme, LVM breaks down the backing storage (called physical volumes) into many small chunks called physical extents (PE) which are typically 4MB in size. These physical extents are assigned to their respective logical volumes (referred to as Logical Extents) and can be added or removed after creation allowing for volumes to grow or shrink as needed. One of the added benefits with this design allows for the ability to implement copy-on-write (COW) allowing for quick and space-efficient snapshotting.

	===Creating a volume group and logical volume===		===Creating a volume group and logical volume===
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	# vgrename uga ug_vg		# vgrename uga ug_vg
	}}		}}

			==== Mounting and unmounting a volume ====
			LVM volumes are exposed as a block device. You will need to format a filesystem of your choice and then mount it like any other device.

			Continuing with the example above, we can mount <code>/dev/ug_vg/ug</code> as an ext4 filesystem with the usual mount command:
			{{Highlight
			\| code = # mount /dev/ug_vg/ug /mnt/ug
			# umount /mnt/ug
			\| lang = terminal
			}}
			Similarly, you can add the filesystem to the <code>/etc/fstab</code> file so it is mounted automatically on start up.

	===Using snapshots===		===Using snapshots===
	A snapshot creates a point-in-time copy of a volume. Unlike ZFS, a LVM snapshot creates a separate volume which appears as a separate block device which needs to be mounted separately. There is no need to worry about creating an unclean filesystem with the snapshot because LVM will make the necessary system calls and work so that the filesystem is synced and checkpointed so that the snapshot copy is consistent and clean.		A snapshot creates a point-in-time copy of a volume. Unlike ZFS, a LVM snapshot creates a separate volume which appears as a separate block device which needs to be mounted separately. There is no need to worry about creating an unclean filesystem with the snapshot because LVM will make the necessary system calls and work so that the filesystem is synced and checkpointed so that the snapshot copy is consistent and clean.

	==== Creating, listing, and deleting snapshots ====		====Creating, listing, and deleting snapshots====
	To create a new snapshot of an existing volume, use the <code>lvcreate</code> command with the <code>-s</code> or <code>--snapshot</code> option. You will need to specify the size of the snapshot. More on this later. Once created, the snapshot will appear in <code>lvs</code> with a <code>s</code> attribute and can be removed with the <code>lvremove</code> command.		To create a new snapshot of an existing volume, use the <code>lvcreate</code> command with the <code>-s</code> or <code>--snapshot</code> option. You will need to specify the size of the snapshot. More on this later. Once created, the snapshot will appear in <code>lvs</code> with a <code>s</code> attribute and can be removed with the <code>lvremove</code> command.
	{{Highlight		{{Highlight
Line 116:		Line 130:
	}}		}}

	==== Snapshot volume size ====		====Snapshot volume size====
	A new snapshot takes nearly no additional space. Any changes that are made to the origin volume or the snapshotted volume will need to be tracked in order for the snapshot to function. This is done transparently through the copy-on-write feature of LVM, but unlike ZFS, the size requirement of this copy-on-write is deducted from the snapshot volume rather than the whole storage pool as a whole. In other words, as the source volume or snapshot volume changes, the size requirement of the snapshot volume will grow in tandem to a maximum of the source volume size.		A new snapshot takes nearly no additional space. Any changes that are made to the origin volume or the snapshotted volume will need to be tracked in order for the snapshot to function. This is done transparently through the copy-on-write feature of LVM, but unlike ZFS, the size requirement of this copy-on-write is deducted from the snapshot volume rather than the whole storage pool as a whole. In other words, as the source volume or snapshot volume changes, the size requirement of the snapshot volume will grow in tandem to a maximum of the source volume size.

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	You may also configure LVM to automatically extend snapshot volumes by editing <code>/etc/lvm/lvm.conf</code> and setting the <code>snapshot_autoextend_threshold</code> value.		You may also configure LVM to automatically extend snapshot volumes by editing <code>/etc/lvm/lvm.conf</code> and setting the <code>snapshot_autoextend_threshold</code> value.

	===Recovering ~~Volumes~~===		== Tasks ==

			===Recovering lost volumes===
	{{highlight\|lang=terminal\|code=		{{highlight\|lang=terminal\|code=
	# vgscan # Generates /etc/lvm/backup/VolGroup01		# vgscan # Generates /etc/lvm/backup/VolGroup01
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	*http://thecususergroup.proboards.com/thread/4156/recover-thecus-raid-pc		*http://thecususergroup.proboards.com/thread/4156/recover-thecus-raid-pc

	===~~Mounting / Unmounting Volumes===~~		=== Expanding an existing volume ===
	~~If you have a LVM partition, you can see what physical volumes there are under the LVM by running:~~

	~~{{highlight\|lang=terminal\|code=~~
	~~# pvs~~
	~~PV VG Fmt Attr PSize PFree~~
	~~/dev/hda2 VolGroup01 lvm2 a- 148.94G 32.00M~~
	}}

	~~The volume group (VG) is {{code\|VolumeGroup01}}. To view the logical volumes under this volume group, run:~~

	~~{{highlight\|lang=terminal\|code=~~
	~~# lvdisplay /dev/VolumeGroup01~~
	}}

	~~Once you have located the logical~~ volume ~~you want to mount, say {{code\|LogVol00}}, run:~~

	~~{{highlight\|lang~~=~~terminal\|code=~~
	~~# mount /dev/VolumeGroup01/LogVol00 /mnt/disk~~
	}}


	~~==Expanding Volume~~==
	Here's a quick guide on expanding a virtual disk that is using LVM.		Here's a quick guide on expanding a virtual disk that is using LVM.

Leo: snapshot extend size

2021-04-22T21:57:24Z

snapshot extend size

← Older revision		Revision as of 21:57, 22 April 2021
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	\|<code>lvcreate -n lv_name -l 50%FREE vg_name</code>		\|<code>lvcreate -n lv_name -l 50%FREE vg_name</code>
	<code>lvcreate -n lv_name -L 50G vg_name</code>		<code>lvcreate -n lv_name -L 50G vg_name</code>
			\|-
			\|Create a snapshot capable of holding 10G of deltas
			\|<code>lvcreate -s -n snap_lv_name --size 10G /dev/vg_name/lv_name</code>
	\|-		\|-
	\|Resize a logical volume, <code>+Size</code> to increase, <code>-Size</code> to decrease.		\|Resize a logical volume, <code>+Size</code> to increase, <code>-Size</code> to decrease.
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	LVM allows the creation of volumes which functionally is similar to partitions. This is done by allocating storage into a volume group (VG) which can then be broken up into separate logical volumes (LV).		LVM allows the creation of volumes which functionally is similar to partitions. This is done by allocating storage into a volume group (VG) which can then be broken up into separate logical volumes (LV).

	Unlike a traditional partition scheme, LVM breaks down the backing storage into many small chunks called physical extents (PE) which are typically 4MB in size. These physical extents are assigned to their respective logical volumes (referred to as Logical Extents) and can be added or removed after creation allowing for volumes to grow or shrink as needed. One of the added benefits with this design allows for the ability to implement copy-on-write (~~CoW~~) allowing for quick and space-efficient snapshotting.		Unlike a traditional partition scheme, LVM breaks down the backing storage into many small chunks called physical extents (PE) which are typically 4MB in size. These physical extents are assigned to their respective logical volumes (referred to as Logical Extents) and can be added or removed after creation allowing for volumes to grow or shrink as needed. One of the added benefits with this design allows for the ability to implement copy-on-write (COW) allowing for quick and space-efficient snapshotting.

	=== Creating a volume group and logical volume ===		===Creating a volume group and logical volume===

	To quickly get a filesystem up and running using LVM, we will need to create a volume group and then a logical volume within the volume group.{{highlight\|lang=terminal\|code=		To quickly get a filesystem up and running using LVM, we will need to create a volume group and then a logical volume within the volume group.{{highlight\|lang=terminal\|code=
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	}}		}}

	=== Using snapshots ===		===Using snapshots===
	A snapshot creates a point-in-time copy of a volume. Unlike ZFS, a LVM snapshot creates a separate volume which appears as a separate block device which needs to be mounted separately. There is no need to worry about creating an unclean filesystem with the snapshot because LVM will make the necessary system calls and work so that the filesystem is synced and checkpointed so that the snapshot copy is consistent and clean.		A snapshot creates a point-in-time copy of a volume. Unlike ZFS, a LVM snapshot creates a separate volume which appears as a separate block device which needs to be mounted separately. There is no need to worry about creating an unclean filesystem with the snapshot because LVM will make the necessary system calls and work so that the filesystem is synced and checkpointed so that the snapshot copy is consistent and clean.

			==== Creating, listing, and deleting snapshots ====
	To create a new snapshot of an existing volume, use the <code>lvcreate</code> command with the <code>-s</code> or <code>--snapshot</code> option. You will need to specify the size of the snapshot. More on this later. Once created, the snapshot will appear in <code>lvs</code> with a <code>s</code> attribute and can be removed with the <code>lvremove</code> command.		To create a new snapshot of an existing volume, use the <code>lvcreate</code> command with the <code>-s</code> or <code>--snapshot</code> option. You will need to specify the size of the snapshot. More on this later. Once created, the snapshot will appear in <code>lvs</code> with a <code>s</code> attribute and can be removed with the <code>lvremove</code> command.
	{{Highlight		{{Highlight
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	\| lang = terminal		\| lang = terminal
	}}		}}
	A new snapshot takes nearly no additional space. Any changes that are made to the origin volume or the snapshotted volume will need to be tracked in order for the snapshot to function. This is done transparently through the copy-on-write feature of LVM, but unlike ZFS, the size requirement of this copy-on-write is deducted from the snapshot volume rather than the whole storage pool as a whole. In other words, as the source volume or snapshot volume changes, the size requirement of the snapshot volume will grow in tandem to a maximum of the source volume size. On a busy filesystem or for snapshots that you intend to keep around for a long time, the snapshot size should match the source volume size. The snapshot will become corrupt when the snapshot volume runs out of space.
			==== Snapshot volume size ====
			A new snapshot takes nearly no additional space. Any changes that are made to the origin volume or the snapshotted volume will need to be tracked in order for the snapshot to function. This is done transparently through the copy-on-write feature of LVM, but unlike ZFS, the size requirement of this copy-on-write is deducted from the snapshot volume rather than the whole storage pool as a whole. In other words, as the source volume or snapshot volume changes, the size requirement of the snapshot volume will grow in tandem to a maximum of the source volume size.

			On a busy filesystem or for snapshots that you intend to keep around for a long time, the snapshot size should match the source volume size. '''The snapshot will become corrupt when the snapshot volume runs out of space.'''

			If you have a snapshot that is about to run out of space, increase the snapshot volume size with <code>lvextend</code>:
			{{Highlight
			\| code = # lvextend -L +10G /dev/volgroup/logicalvol_snap
			\| lang = terminal
			}}
			You may also configure LVM to automatically extend snapshot volumes by editing <code>/etc/lvm/lvm.conf</code> and setting the <code>snapshot_autoextend_threshold</code> value.

	===Recovering Volumes===		===Recovering Volumes===

Leo: snapshot

2021-04-22T21:43:53Z

snapshot

← Older revision		Revision as of 21:43, 22 April 2021
Line 41:		Line 41:
	==Introduction==		==Introduction==
	[[File:LVM Overview.svg\|alt=Logical Volume Manager, showing disks to physical extents to volume groups to logical volumes\|thumb\|Logical Volume Manager, showing disks to physical extents to volume groups to logical volumes]]		[[File:LVM Overview.svg\|alt=Logical Volume Manager, showing disks to physical extents to volume groups to logical volumes\|thumb\|Logical Volume Manager, showing disks to physical extents to volume groups to logical volumes]]
	LVM allows the creation of volumes which functionally is similar to partitions. This is done by allocating storage into a ~~Volume Group~~ (VG) which can then be broken up into separate ~~Logical Volumes~~ (LV).		LVM allows the creation of volumes which functionally is similar to partitions. This is done by allocating storage into a volume group (VG) which can then be broken up into separate logical volumes (LV).

	Unlike a traditional partition scheme, LVM breaks down the backing storage into many small chunks called ~~Physical Extents~~ (PE) which are typically 4MB in size. These physical extents are assigned to their respective logical volumes (referred to as Logical Extents) and can be added or removed after creation allowing for volumes to grow or shrink as needed. One of the added benefits with this design allows for the ability to implement ~~Copy~~ on ~~Write~~ (CoW) allowing for quick and space-efficient snapshotting.		Unlike a traditional partition scheme, LVM breaks down the backing storage into many small chunks called physical extents (PE) which are typically 4MB in size. These physical extents are assigned to their respective logical volumes (referred to as Logical Extents) and can be added or removed after creation allowing for volumes to grow or shrink as needed. One of the added benefits with this design allows for the ability to implement copy-on-write (CoW) allowing for quick and space-efficient snapshotting.

	To quickly get a filesystem up and running using LVM:{{highlight\|lang=terminal\|code=		=== Creating a volume group and logical volume ===

			To quickly get a filesystem up and running using LVM, we will need to create a volume group and then a logical volume within the volume group.{{highlight\|lang=terminal\|code=

	# vgcreate ug_vg /dev/sdb		# vgcreate ug_vg /dev/sdb
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	# vgrename uga ug_vg		# vgrename uga ug_vg
	}}		}}

			=== Using snapshots ===
			A snapshot creates a point-in-time copy of a volume. Unlike ZFS, a LVM snapshot creates a separate volume which appears as a separate block device which needs to be mounted separately. There is no need to worry about creating an unclean filesystem with the snapshot because LVM will make the necessary system calls and work so that the filesystem is synced and checkpointed so that the snapshot copy is consistent and clean.

			To create a new snapshot of an existing volume, use the <code>lvcreate</code> command with the <code>-s</code> or <code>--snapshot</code> option. You will need to specify the size of the snapshot. More on this later. Once created, the snapshot will appear in <code>lvs</code> with a <code>s</code> attribute and can be removed with the <code>lvremove</code> command.
			{{Highlight
			\| code = # lvcreate --size 1G -s -n logicalvol_snap /dev/mapper/volgroup-logicalvol
			Logical volume "logicalvol_snap" created.

			# lvs
			LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
			logicalvol volgroup owi-aos--- 220.00g
			logicalvol_snap volgroup swi-a-s--- 1.00g logicalvol 29.54

			# lvremove -f /dev/volgroup/logicalvol_snap
			Logical volume "metrics_snap" successfully removed
			\| lang = terminal
			}}
			A new snapshot takes nearly no additional space. Any changes that are made to the origin volume or the snapshotted volume will need to be tracked in order for the snapshot to function. This is done transparently through the copy-on-write feature of LVM, but unlike ZFS, the size requirement of this copy-on-write is deducted from the snapshot volume rather than the whole storage pool as a whole. In other words, as the source volume or snapshot volume changes, the size requirement of the snapshot volume will grow in tandem to a maximum of the source volume size. On a busy filesystem or for snapshots that you intend to keep around for a long time, the snapshot size should match the source volume size. The snapshot will become corrupt when the snapshot volume runs out of space.

	===Recovering Volumes===		===Recovering Volumes===