Linux – LVM Volume Attributes

刺骨的言语ヽ痛彻心扉 2023-10-08 09:46 27阅读 0赞

**Redhat Linux – LVM Volume Attributes**

AUGUST 25, 2013 BY [LINGESWARAN R][] [1 COMMENT][]

[LVM][]

*  [How to Install LVM on Linux and Disk Operations][]
 *  [Linux – LVM – Volume Group Operations][Linux _ LVM _ Volume Group Operations]
 *  [Linux LVM – Volume Creation & Operations][Linux LVM _ Volume Creation _ Operations]
 *  [Linux LVM – Re-sizing the Logical Volume][Linux LVM _ Re-sizing the Logical Volume]
 *  [Redhat Linux – LVM Volumes Re-layout][Redhat Linux _ LVM Volumes Re-layout]
 *  [Linux LVM – How to take volume snapshot][Linux LVM _ How to take volume snapshot]
 *  Redhat Linux – LVM Volume Attributes
 *  [LVM- Linux Interview Questions][]
 *  [RedhatLinux SAN Migration using LVM][]

Redhat Linux’s Logical volume Manager has many attributes which are available for controlling the behavior LVM objects or to changing the default values of LVM. We may not use those attributes very often in typical production environment but knowing is not a bad thing. As a Unix/Linux admin,we should have capability to explain each and every field of commands output as most of the fields will reflect the attributes value.Here we will see some of LVM attributes.

**Physical volume(PV) attributes:**

To check the physical volume attributes,use “pvs” command.The forth column of pvs command output displays the physical volume attributes.

\[root@mylinz ~\]\# pvs

PV VG Fmt Attr PSize PFree

/dev/sda2 vg\_mylinz lvm2 a- 19.51g 0

/dev/sdd1 uavg lvm2 a- 508.00m 408.00m

/dev/sde uavg lvm2 a- 508.00m 508.00m

/dev/sdf uavg lvm2 a- 5.00g 5.00g

\[root@mylinz ~\]\#

The above command output shows “a” in the attribute field which explains that physical volumes can be “allocated” to the volumes.

Export the volume group “uavg” and check pvs output.

\[root@mylinz ~\]\# vgexport uavg

Volume group "uavg" successfully exported

\[root@mylinz ~\]\# pvs

PV VG Fmt Attr PSize PFree

/dev/sda2 vg\_mylinz lvm2 a- 19.51g 0

/dev/sdd1 uavg lvm2 ax 508.00m 408.00m

/dev/sde uavg lvm2 ax 508.00m 508.00m

/dev/sdf uavg lvm2 ax 5.00g 5.00g

\[root@mylinz ~\]\#

In attributes field, you can see that “x” is added now.This show that volume group is exported.

We can stop the allocation to the disk by using pvchnage command.By disabling allocation,volume will not be extended using that specific physical volume.

\[root@mylinz ~\]\# pvchange -x n /dev/sdd1

Physical volume "/dev/sdd1" changed

1 physical volume changed / 0 physical volumes not changed

\[root@mylinz ~\]\# pvs

PV VG Fmt Attr PSize PFree

/dev/sda2 vg\_mylinz lvm2 a- 19.51g 0

/dev/sdd1 uavg lvm2 -- 508.00m 408.00m

/dev/sde uavg lvm2 a- 508.00m 508.00m

/dev/sdf uavg lvm2 a- 5.00g 5.00g

\[root@mylinz ~\]\#

You can revert the change any time using below mentioned command.

\[root@mylinz ~\]\# pvchange -x y /dev/sdd1

Physical volume "/dev/sdd1" changed

1 physical volume changed / 0 physical volumes not changed

\[root@mylinz ~\]\# pvs

PV VG Fmt Attr PSize PFree

/dev/sda2 vg\_mylinz lvm2 a- 19.51g 0

/dev/sdd1 uavg lvm2 a- 508.00m 408.00m

/dev/sde uavg lvm2 a- 508.00m 508.00m

/dev/sdf uavg lvm2 a- 5.00g 5.00g

\[root@mylinz ~\]\#

Some of the useful commands to get the details of physical volume.  
1.To get the physical volumes with “UID” , use “-v” option.  
Note:You can also use “pvs -vv” to get more detailed information.

\[root@mylinz ~\]\# pvs -v

Scanning for physical volume names

PV VG Fmt Attr PSize PFree DevSize PV UUID

/dev/sdd1 uavg lvm2 ax 508.00m 408.00m 511.98m tJ5YhP-VOZV-yfQ6-Uyye-WGT7-VLcl-7M3RMK

/dev/sde uavg lvm2 ax 508.00m 508.00m 512.00m FadWLT-LjD8-v8VB-pboY-eZbK-vYpE-ZWq0i9

/dev/sdf uavg lvm2 ax 5.00g 5.00g 5.00g GbvgWh-l0w3-wCA6-umkD-zfsS-8yAZ-GeOSKF

\[root@mylinz ~\]\#

2.To get all the disks connected to the system ,use “pvs -a”

\[root@mylinz ~\]\# pvs -a

PV VG Fmt Attr PSize PFree

/dev/root -- 0 0

/dev/sda1 -- 0 0

/dev/sda2 vg\_mylinz lvm2 a- 19.51g 0

/dev/sdb1 -- 0 0

/dev/sdc1 -- 0 0

/dev/sdd1 uavg lvm2 ax 508.00m 408.00m

/dev/sde uavg lvm2 ax 508.00m 508.00m

/dev/sdf uavg lvm2 ax 5.00g 5.00g

/dev/sdg -- 0 0

/dev/vg\_mylinz/lv\_swap -- 0 0

\[root@mylinz ~\]\#

/dev/sda1 is not part of LVM but you get the disk list in pvs command.  
  
3.To get the segment wise output,use below command.

\[root@mylinz ~\]\# pvs --segments

PV VG Fmt Attr PSize PFree Start SSize

/dev/sda2 vg\_mylinz lvm2 a- 19.51g 0 0 4234

/dev/sda2 vg\_mylinz lvm2 a- 19.51g 0 4234 760

/dev/sdd1 uavg lvm2 ax 508.00m 408.00m 0 13

/dev/sdd1 uavg lvm2 ax 508.00m 408.00m 13 25

/dev/sdd1 uavg lvm2 ax 508.00m 408.00m 38 89

/dev/sde uavg lvm2 ax 508.00m 508.00m 0 127

/dev/sdf uavg lvm2 ax 5.00g 5.00g 0 1279

\[root@mylinz ~\]\#

**Volume Group(VG) Attributes:**

You can see the volume group attributes using vgs command.  
table.tableizer-table \{ border: 1px solid \#CCC; font-family: Arial, Helvetica, sans-serif font-size: 12px; \} .tableizer-table td \{ padding: 4px; margin: 3px; border: 1px solid \#ccc; \} .tableizer-table th \{ background-color: \#104E8B; color: \#FFF; font-weight: bold; \}

<table> 
 <tbody> 
 <tr> 
 <td> ATTRIBUTES </td> 
 <td> DESCRIPTION </td> 
 </tr> 
 <tr> 
 <td> r,w </td> 
 <td> (r)ead &amp; (w)rite permissions </td> 
 </tr> 
 <tr> 
 <td> z </td> 
 <td> resi(z)eable </td> 
 </tr> 
 <tr> 
 <td> x </td> 
 <td> e(x)ported </td> 
 </tr> 
 <tr> 
 <td> p </td> 
 <td> (p)artial </td> 
 </tr> 
 <tr> 
 <td> c,n,a,i </td> 
 <td> allocation policy (c)ontiguous, c(l)ing, (n)ormal, (a)nywhere, (i)nherited </td> 
 </tr> 
 <tr> 
 <td> c </td> 
 <td> (c)luster </td> 
 </tr> 
 </tbody> 
</table>

Here we will see sample vgs command output.

\[root@mylinz ~\]\# vgs

VG \#PV \#LV \#SN Attr VSize VFree

uavg 3 1 0 wz--n- 5.99g 5.89g

vg\_mylinz 1 2 0 wz--n- 19.51g 0

\[root@mylinz ~\]\#

\[root@mylinz ~\]\# vgs -v

Finding all volume groups

Finding volume group "uavg"

Finding volume group "vg\_mylinz"

VG Attr Ext \#PV \#LV \#SN VSize VFree VG UUID

uavg wz--n- 4.00m 3 1 0 5.99g 5.89g c87FyZ-5DND-oQ3n-iTh1-Vb1f-nBML-vUBUE9

vg\_mylinz wz--n- 4.00m 1 2 0 19.51g 0 dIgmLP-aoe3-anxY-WHYE-bBtX-u28M-WF6Ye5

\[root@mylinz ~\]\#

There are some other volume group attributes which will be useful while creating the new volume group.

table.tableizer-table \{ border: 1px solid \#CCC; font-family: Arial, Helvetica, sans-serif font-size: 12px; \} .tableizer-table td \{ padding: 4px; margin: 3px; border: 1px solid \#ccc; \} .tableizer-table th \{ background-color: \#104E8B; color: \#FFF; font-weight: bold; \}

<table> 
 <tbody> 
 <tr> 
 <td> ATTRIBUTES </td> 
 <td> DESCRIPTION </td> 
 </tr> 
 <tr> 
 <td> -l </td> 
 <td> &nbsp;maximum logical volumes </td> 
 </tr> 
 <tr> 
 <td> -p </td> 
 <td> maximum physical volumes </td> 
 </tr> 
 <tr> 
 <td> -s </td> 
 <td> physical extent size (default is 4MB) </td> 
 </tr> 
 <tr> 
 <td> -A </td> 
 <td> autobackup </td> 
 </tr> 
 </tbody> 
</table>

All the above mentioned attributes can be set while creating the volume group.You can not modify those values after that.In the below example,I have used most the attributes with specific value to create new volume group.

\[root@mylinz ~\]\# vgcreate -l 512 -p 256 -s 32M -Ay newvg /dev/sdf

Volume group "newvg" successfully created

vgs newvg

VG \#PV \#LV \#SN Attr VSize VFree

newvg 1 0 0 wz--n- 4.97g 4.97g

\[root@mylinz ~\]\#

You can see the newly set values in vgdisplay command output.

\[root@mylinz ~\]\# vgdisplay -v newvg

Using volume group(s) on command line

Finding volume group "newvg"

\--- Volume group ---

VG Name newvg

System ID

Format lvm2

Metadata Areas 1

Metadata Sequence No 1

VG Access read/write

VG Status resizable

MAX LV 512

Cur LV 0

Open LV 0

Max PV 256

Cur PV 1

Act PV 1

VG Size 4.97 GiB

PE Size 32.00 MiB

Total PE 159

Alloc PE / Size 0 / 0

Free PE / Size 159 / 4.97 GiB

VG UUID Ny4xsv-uJ49-sZr9-lvfq-Oa7n-l5mH-1bPBbp

\--- Physical volumes ---

PV Name /dev/sdf

PV UUID GbvgWh-l0w3-wCA6-umkD-zfsS-8yAZ-GeOSKF

PV Status allocatable

Total PE / Free PE 159 / 159

\[root@mylinz ~\]\#

**Logical Volume (LV) Attributes:**

Knowing the logical volume attributes.

\[root@mylinz ~\]\# lvs

LV VG Attr LSize Origin Snap% Move Log Copy% Convert

vol1 uavg -wi-ao 100.00m

lv\_root vg\_mylinz -wi-ao 16.54g

lv\_swap vg\_mylinz -wi-ao 2.97g

\[root@mylinz ~\]\#

The below tables covers the “lvs” command attributes. table.tableizer-table \{ border: 1px solid \#CCC; font-family: Arial, Helvetica, sans-serif font-size: 12px; \} .tableizer-table td \{ padding: 4px; margin: 3px; border: 1px solid \#ccc; \} .tableizer-table th \{ background-color: \#104E8B; color: \#FFF; font-weight: bold; \}

<table> 
 <tbody> 
 <tr> 
 <td> VOLUME TYPE ATTRIBUTES(FIRST FIELD OF ATTR) </td> 
 <td> DESCRIPTION </td> 
 </tr> 
 <tr> 
 <td> m </td> 
 <td> (m)irrored </td> 
 </tr> 
 <tr> 
 <td> M </td> 
 <td> (M)irrored without intial sync </td> 
 </tr> 
 <tr> 
 <td> o </td> 
 <td> (o)rgin </td> 
 </tr> 
 <tr> 
 <td> p </td> 
 <td> (p)vmove </td> 
 </tr> 
 <tr> 
 <td> s </td> 
 <td> (s)napshot </td> 
 </tr> 
 <tr> 
 <td> S </td> 
 <td> invalid (S)napshot </td> 
 </tr> 
 <tr> 
 <td> v </td> 
 <td> (v)irtual </td> 
 </tr> 
 <tr> 
 <td> i </td> 
 <td> mirror (i)mage </td> 
 </tr> 
 <tr> 
 <td> l </td> 
 <td> mirror (I)mage without sync </td> 
 </tr> 
 <tr> 
 <td> c </td> 
 <td> under (c)onstruction </td> 
 </tr> 
 <tr> 
 <td> – </td> 
 <td> Simple Volume </td> 
 </tr> 
 </tbody> 
</table>

<table> 
 <tbody> 
 <tr> 
 <td> ATTRIBUTES (SECOND TO SIXTH FIELD OF ATTR) </td> 
 <td> DESCRIPTION </td> 
 </tr> 
 <tr> 
 <td> w,r (Second Feild) </td> 
 <td> Permissions ‘(r)’ead ‘(w)’rite </td> 
 </tr> 
 <tr> 
 <td> c,I,n.a,I (Third Feild) </td> 
 <td> Allocation policy (c)ontiguous, c(l)ing, (n)ormal, (a)nywhere, (i)nherited </td> 
 </tr> 
 <tr> 
 <td> m (Fourth Feild) </td> 
 <td> Fixed (m)inor </td> 
 </tr> 
 <tr> 
 <td> a,s,I (Fifth Feild) </td> 
 <td> (a)ctive, (s)uspended, (I)nvalid snapshot,, </td> 
 </tr> 
 <tr> 
 <td> S (Fifth Feild) </td> 
 <td> Invalid (S)uspended snapshot </td> 
 </tr> 
 <tr> 
 <td> I (Fifth Feild) </td> 
 <td> Mapped device present with (i)nactive table </td> 
 </tr> 
 <tr> 
 <td> d (Fifth Feild) </td> 
 <td> Mapped (d)evice present with-out tables </td> 
 </tr> 
 <tr> 
 <td> o (sixth Feild) </td> 
 <td> device (o)pen (Volume is in active state or may be mounted ) </td> 
 </tr> 
 </tbody> 
</table>

While creating the volume can provide various attributes like stripe size,no of extends

etc.These are already covered in [volume creation][].  
  
Here we will see some of the useful “lvs” command options.  
1.To display the logical volumes with underlying physical volumes use,

\[root@mylinz ~\]\# lvs -a -o +devices

LV VG Attr LSize Origin Snap% Move Log Copy% Convert Devices

vol1 uavg -wi-ao 100.00m /dev/sdd1(13)

lv\_root vg\_mylinz -wi-ao 16.54g /dev/sda2(0)

lv\_swap vg\_mylinz -wi-ao 2.97g /dev/sda2(4234)

\[root@mylinz ~\]\#

2.To see the complete physical disks segmnets for logical volumes,

\[root@mylinz ~\]\# lvs -a -o +seg\_pe\_ranges --segments

LV VG Attr \#Str Type SSize PE Ranges

vol1 uavg -wi-ao 1 linear 100.00m /dev/sdd1:13-37

lv\_root vg\_mylinz -wi-ao 1 linear 16.54g /dev/sda2:0-4233

lv\_swap vg\_mylinz -wi-ao 1 linear 2.97g /dev/sda2:4234-4993

\[root@mylinz ~\]\#

3.For detailed logical volume information,

\[root@mylinz ~\]\# lvdisplay --maps /dev/uavg/vol1

\--- Logical volume ---

LV Name /dev/uavg/vol1

VG Name uavg

LV UUID XjMpRC-6f5k-FN9L-jz5v-f0Gj-wBpf-xc9GVD

LV Write Access read/write

LV Status available

\# open 1

LV Size 100.00 MiB

Current LE 25

Segments 1

Allocation inherit

Read ahead sectors auto

\- currently set to 256

Block device 253:2

\--- Segments ---

Logical extent 0 to 24:

Type linear

Physical volume /dev/sdd1

Physical extents 13 to 37

\[root@mylinz ~\]\#

Hope this post is informative for you.Thank you for reading this article.Please leave a comment if you have any doubt.I will get back to you.

[LINGESWARAN R]: https://www.unixarena.com/author/lingeswaran-r/
[1 COMMENT]: https://www.unixarena.com/2013/08/redhat-linux-lvm-volume-attributes.html/#comments
[LVM]: https://www.unixarena.com/series/lvm/
[How to Install LVM on Linux and Disk Operations]: https://www.unixarena.com/2013/08/how-to-install-lvm-on-linux-and-disk.html/
[Linux _ LVM _ Volume Group Operations]: https://www.unixarena.com/2013/08/linux-lvm-volume-group-operations.html/
[Linux LVM _ Volume Creation _ Operations]: https://www.unixarena.com/2013/08/linux-lvm-volume-creation-operation.html/
[Linux LVM _ Re-sizing the Logical Volume]: https://www.unixarena.com/2013/08/linux-lvm-re-sizing-logical-volume.html/
[Redhat Linux _ LVM Volumes Re-layout]: https://www.unixarena.com/2013/08/redhat-linux-lvm-volumes-re-layout.html/
[Linux LVM _ How to take volume snapshot]: https://www.unixarena.com/2013/08/linux-lvm-how-to-take-volume-snapshot.html/
[LVM- Linux Interview Questions]: https://www.unixarena.com/2013/08/lvm-linux-interview-questions.html/
[RedhatLinux SAN Migration using LVM]: https://www.unixarena.com/2012/07/redhatlinux-san-migration-using-lvm.html/
[volume creation]: https://www.unixarena.com/2013/08/linux-lvm-volume-creation-operation.html