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LVM Cheatsheet

Directory and Files Tools Physical Volumes Volume Groups Logical Volumes Miscellaneous
The Linux Logical
Volume Manager (LVM)
   

Random Findings

Humor

Etc

Material of this page is based on RedHat - LVM cheatsheet

This is a quick and dirty cheat sheet on LVM using Linux.

I have highlighted many of the common attributes for each command however this is not an extensive list, make sure you look up the man page for the command.

With the pvs, vgs and lvs commands, the number of -v defines that level of "verbosity": the more v you put, the more verbose information is produced.

For example

pvs -vvvvv 

Display, scanning, listing of physical volumes (PV)

pvdisplay -v 
pvs -v 
pvs -a 
pvs attributes are:
  1. (a)llocatable
  2. e(x)ported
pvscan -v

Note: scans for disks for non-LVM and LVM disks

Diagnostic

lvmdump
lvmdump -d <dir>
dmsetup [info|ls|status] 
Note: by default the lvmdump command creates a tar ball Physical Volumes

Adding

pvcreate /dev/sdb1

Create physical volume with specific UUID, used to recover volume groups (see miscellaneous section)

pvcreate --uuid <UUID> /dev/sdb1 

Common Attributes that you may want to use:

-M2 create a LVM2 physical volume

Removing

checking
pvck -v /dev/sdb1 
Note: check the consistency of the LVM metadata

Change physical attributes

do not allow allocation of extents on this drive

pvchange -x n /dev/sdb1

Common Attributes that you may want to use:

--addtag add a tag
-x allowed to allocate extents
-u change the uuid

Moving

pvmove -v /dev/sdb2 /dev/sdb3 

Note: moves any used extents from this volume to another volume, in readiness to remove that volume. However you cannot use this on mirrored volumes, you must convert back to non-mirror using "lvconvert -m 0"

Volume Groups

Display

vgdisplay -v 			
vgs -v
vgs -a -o +devices
vgs flags:vgs attributes are:

1. permissions (r)|(w)
2. resi(z)eable
3. e(x)ported
4. (p)artial
5. allocation policy - (c)ontiguous, c(l)ing, (n)ormal, (a)nywhere, (i)nherited
6. (c)luster

Scanning

vgscan -v 

Creating

vgcreate VolData00 /dev/sdb1 /dev/sdb2 /dev/sdb3
vgcreate VolData00 /dev/sdb[123]
Use 32MB extent size
vgcreate VolData00 -s 32 /dev/sdb1 
Common Attributes that you may want to use:

Extending

vgextend VolData00 /dev/sdb3 

Reducing

vgreduce VolData00 /dev/sdb3
			
vgreduce --removemissing --force VolData00 

Removing

vgremove VolData00

Common Attributes that you may want to use:

Checking

vgck VolData00 
Note: checks the consistency of the LVM metadata

Change volume attributes

vgchange -a n VolData00
Common Attributes that you may want to use:

Renaming

vgrename VolData00 Data_Vol_01
Note: the volume group must not have any active logical volumes

Converting metadata type

vgconvert -M2 VolData00
Note: vgconvert allows you to convert from one type of metadata format to another for example from LVM1 to LVM2

Merging

vgmerge New_Vol_Group Old_Vol_Group
Note: the old volumes group will be merged into the new volume group

Spliting

vgsplit Old_Vol_Group New_Vol_Group [physical volumes] [-n logical volume name] 

Importing

vgimport VolData00
Common Attributes that you may want to use:

Exporting

To see if a volume has already been export use "vgs" and look at the third attribute should be a x
vgexport VolData00
Common Attributes that you may want to use:

Backing up

Backup to default location (/etc/lvm/backup)
vgcfgbackup VolData00
Backup to specific location
vgcfgbackup -f /var/backup/VolData00_bkup VolData00

Note: the backup is written in plain text and are by default located in /etc/lvm/backup

Restoring

vgcfgrestore -f /var/backup/VolData00_bkup VolData00
Common Attributes that you may want to use:

-l list backups of file
-f backup file
-M metadataype 1 or 2

Cloning

vgimportclone /dev/sdb1
Note: used to import and rename duplicated volume group

Special files

vgmknodes VolData00
Note: recreates volume group directory and logical volume special files in /dev

Logical Volumes

Display

lvdisplay -v 
display mirror volumes
lvdisplay --maps
lvs -v
lvs -a -o +devices

lvs commands for mirror volumes:

lvs -a -o +devices
lvs -a -o +seg_pe_ranges --segments
lvs attributes are:
  1. volume type: (m)irrored, (M)irrored without initail sync, (o)rigin, (p)vmove, (s)napshot, invalid (S)napshot, (v)irtual, mirror (i)mage  mirror (I)mage out-of-sync, under (c)onversion
  2. permissions: (w)rite, (r)ead-only
  3. allocation policy - (c)ontiguous, c(l)ing, (n)ormal, (a)nywhere, (i)nherited
  4. fixed (m)inor
  5. state: (a)ctive, (s)uspended, (I)nvalid snapshot, invalid (S)uspended snapshot, mapped (d)evice present with-out tables,  mapped device present with (i)nactive table
  6. device (o)pen (mounted in other words)

Scanning

lvscan -v 
lvmdiskscan

Creating

Plain old volume

lvcreate -L 10G VolData00

Plain old volume but with a specific name web01:

lvcreate -L 10G -n web01 VolData00 

Plain old volume but on a specific disk

lvcreate -L 10G VolData00 /dev/sdb1

A striped volume called lvol1

lvcreate -i 3 -I 32 -L 24G -n lvol1 vg01

Mirrored volume:

lvcreate -L 10G -m1 -n data01 vg01

Mirrored volume without a mirror log file:

lvcreate -L 10M -m1 --mirrorlog core -n data01 vg01
Common Attributes that you may want to use:

Extending

lvextend -L 20M /dev/VolData00/vol01
Common Attributes that you may want to use:

-L size of the volume [kKmMgGtT]
-l number of extents
-C contiguous [y|n]
-i stripes
-I stripe size

Note: you can extend a ext2/ext3 filesystem using the "resize2fs" or "fsadm" command

fsadm resize /dev/VolData01/data01
resize2fs -p /dev/mapper/VolData01-data01 [size]

The -p option displays bars of progress while extending the filesystem

reducing/resizing

lvreduce -L 5G /dev/VolData00/vol01
lvresize -L 5G /dev/VolData00/vol01
Note: rounding will occur when extending and reducing volumes to the next extent (4MB by default), you can use resize2fs or fsadm to shrink the filesystem

fsadm resize /dev/VolData01/data01 [size]
resize2fs -p /dev/mapper/VolData01-data01 [size]

removing

lvremove /dev/VolData00/vol01

adding a mirror to a non-mirrored volume

lvconvert -m1 --mirrorlog core /dev/VolData00/vol01 /dev/sdb2 

change volume attributes

lvchange -a n /dev/VolData00/vol01
Common Attributes that you may want to use:

-a availability
-C contiguous [y|n]
 

renaming

lvrname /dev/VolData00/vol_old /dev/VolData00/vol_new

snapshotting

lvcreate --size 100M --snapshot -name snap /dev/vg01/data01 

Miscellaneous

Simulating a disk failure
dd if=/dev/zero of=/dev/sdb2 count=10 

Repairing a failed mirror no LVM corruption

Check volume, persume /dev/sdb2 has failed:

lvs -a -o +devices

Remove the failed disk from the volume (if not already done so) , this will convert volume into a non-mirrored volume

vgreduce --removemissing --force VolData00

Replace the disk physically, remember to partion it with type 8e:

fdisk /dev/sdb
........

Add new disk to LVM
pvcreate /dev/sdb2
Add the disk back into volume group
vgextend VolData00 /dev/sdb2

Mirror up the volume:

lvconvert -m1 --mirrorlog core /dev/VolData00/vol02 /dev/sdb2

Repair corrupt LVM metadata without replacing drive

Attempt to bring the volume group online:

vgchange -a y VolData00

Restore the LVM configation

vgcfgrestore VolData00

Attempt to bring the volume group online:

vgchange -a y VolData00 

File system check:

e2fsck /dev/VolData00/data01

Repair corrupt LVM metadata and replace the faulty disk

# attempt to bring the volume group online but you get UUID conflict errors make note of the UUID number
vgchange -a y VolData00
vgchange -a n VolData00

## sometimes it my only be a logical volume problem
lvchange -a y /dev/VolData00/web02
lvchange -a n /dev/Voldata00/web02

## replace the disk physically, remember to partion it with type 8e
fdisk /dev/sdb
........

# after replacing the faulty drive the disk must have the previuos UUID number or you can get it from /etc/lvm directory
pvcreate --uuid <previous UUID number taken from above command> /dev/sdb2

# Restore the LVM configation
vgcfgrestore VolData00

# attempt to bring the volume group online or logical volume
vgchange -a y VolData00
lvchange -a y /dev/VolData00/web02

# file system check
e2fsck /dev/VolData00/data01

Note: if you have backed the volume group configuration you can obtain the UUID number in the backup file by default located in /etc/lvm/backup or running "pvs -v"

Directory and Files

Directories

Files



Etc

Society

Groupthink : Two Party System as Polyarchy : Corruption of Regulators : Bureaucracies : Understanding Micromanagers and Control Freaks : Toxic Managers :   Harvard Mafia : Diplomatic Communication : Surviving a Bad Performance Review : Insufficient Retirement Funds as Immanent Problem of Neoliberal Regime : PseudoScience : Who Rules America : Neoliberalism  : The Iron Law of Oligarchy : Libertarian Philosophy

Quotes

War and Peace : Skeptical Finance : John Kenneth Galbraith :Talleyrand : Oscar Wilde : Otto Von Bismarck : Keynes : George Carlin : Skeptics : Propaganda  : SE quotes : Language Design and Programming Quotes : Random IT-related quotesSomerset Maugham : Marcus Aurelius : Kurt Vonnegut : Eric Hoffer : Winston Churchill : Napoleon Bonaparte : Ambrose BierceBernard Shaw : Mark Twain Quotes

Bulletin:

Vol 25, No.12 (December, 2013) Rational Fools vs. Efficient Crooks The efficient markets hypothesis : Political Skeptic Bulletin, 2013 : Unemployment Bulletin, 2010 :  Vol 23, No.10 (October, 2011) An observation about corporate security departments : Slightly Skeptical Euromaydan Chronicles, June 2014 : Greenspan legacy bulletin, 2008 : Vol 25, No.10 (October, 2013) Cryptolocker Trojan (Win32/Crilock.A) : Vol 25, No.08 (August, 2013) Cloud providers as intelligence collection hubs : Financial Humor Bulletin, 2010 : Inequality Bulletin, 2009 : Financial Humor Bulletin, 2008 : Copyleft Problems Bulletin, 2004 : Financial Humor Bulletin, 2011 : Energy Bulletin, 2010 : Malware Protection Bulletin, 2010 : Vol 26, No.1 (January, 2013) Object-Oriented Cult : Political Skeptic Bulletin, 2011 : Vol 23, No.11 (November, 2011) Softpanorama classification of sysadmin horror stories : Vol 25, No.05 (May, 2013) Corporate bullshit as a communication method  : Vol 25, No.06 (June, 2013) A Note on the Relationship of Brooks Law and Conway Law

History:

Fifty glorious years (1950-2000): the triumph of the US computer engineering : Donald Knuth : TAoCP and its Influence of Computer Science : Richard Stallman : Linus Torvalds  : Larry Wall  : John K. Ousterhout : CTSS : Multix OS Unix History : Unix shell history : VI editor : History of pipes concept : Solaris : MS DOSProgramming Languages History : PL/1 : Simula 67 : C : History of GCC developmentScripting Languages : Perl history   : OS History : Mail : DNS : SSH : CPU Instruction Sets : SPARC systems 1987-2006 : Norton Commander : Norton Utilities : Norton Ghost : Frontpage history : Malware Defense History : GNU Screen : OSS early history

Classic books:

The Peter Principle : Parkinson Law : 1984 : The Mythical Man-MonthHow to Solve It by George Polya : The Art of Computer Programming : The Elements of Programming Style : The Unix Haterís Handbook : The Jargon file : The True Believer : Programming Pearls : The Good Soldier Svejk : The Power Elite

Most popular humor pages:

Manifest of the Softpanorama IT Slacker Society : Ten Commandments of the IT Slackers Society : Computer Humor Collection : BSD Logo Story : The Cuckoo's Egg : IT Slang : C++ Humor : ARE YOU A BBS ADDICT? : The Perl Purity Test : Object oriented programmers of all nations : Financial Humor : Financial Humor Bulletin, 2008 : Financial Humor Bulletin, 2010 : The Most Comprehensive Collection of Editor-related Humor : Programming Language Humor : Goldman Sachs related humor : Greenspan humor : C Humor : Scripting Humor : Real Programmers Humor : Web Humor : GPL-related Humor : OFM Humor : Politically Incorrect Humor : IDS Humor : "Linux Sucks" Humor : Russian Musical Humor : Best Russian Programmer Humor : Microsoft plans to buy Catholic Church : Richard Stallman Related Humor : Admin Humor : Perl-related Humor : Linus Torvalds Related humor : PseudoScience Related Humor : Networking Humor : Shell Humor : Financial Humor Bulletin, 2011 : Financial Humor Bulletin, 2012 : Financial Humor Bulletin, 2013 : Java Humor : Software Engineering Humor : Sun Solaris Related Humor : Education Humor : IBM Humor : Assembler-related Humor : VIM Humor : Computer Viruses Humor : Bright tomorrow is rescheduled to a day after tomorrow : Classic Computer Humor

The Last but not Least Technology is dominated by two types of people: those who understand what they do not manage and those who manage what they do not understand ~Archibald Putt. Ph.D


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