Volume Group Creation

We are now ready to create a Volume Group (VG).  A Volume group acts as a container of resources for Physical Volumes.  So in other words, the total space available to a LV is created from VG's which have partitions or physical volumes (PV's) associated to them.

When a volume group is created, equally sized chucks or extents are defined.  By default, a physical extent size of 4MB is used however this can be altered with a "-s PhysicalExtentSize [kKmMgGtT]" command line switch (more on that in a minute.)

We can increase or decrease the size of a LV by the addition or removal of physical extents to/from the LV.  This is important as there exists some limitations on 2.4 based kernels.  2.4 based kernels have a maximum LV size is 2TB (32-bit CPUs on 2.6 kernels have a maximum LV size of 16TB and 8EB for 64-bit CPUs.)  2.4 based kernels can also only have at most 65534 extents (2.6 kernels do not have this limitation.)  So the only way to reach a full 2TB LV size on a 2.4 based kernel would be with an extent size of 32MB (32 x 65534 = 2097088MB / 1024MB = 2,047GB or 2TB.)

We are now going to create a new Volume Group using a 32MB physical extent size.

1. Lets begin by taking a look at the Volume Groups the are already present on the system
   
   

   [root@Linux01 ~]# vgdisplay --- Volume group --- VG Name VolGroup00 System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 6 VG Access read/write VG Status resizable MAX LV 0 Cur LV 5 Open LV 5 Max PV 0 Cur PV 1 Act PV 1 VG Size 9.88 GB PE Size 32.00 MB Total PE 316 Alloc PE / Size 316 / 9.88 GB Free PE / Size 0 / 0 VG UUID zz6pnX-TR24-jPcE-zHrv-loz5-TPd2-eERHtq

   
   
2. Create a new Volume Group with the name TCPDumpVolGRP using /dev/sdb1, /dev/sdc1 and /dev/sdd1 with a physical extent size of 32 MB
   
   

   [root@Linux01 ~]# vgcreate TCPDumpVolGRP /dev/sdb1 /dev/sdc1 /dev/sdd1 -s 32M Volume group "TCPDumpVolGRP" successfully created [root@Linux01 ~]#

   
   
3. Verfiy the Volume Group was created successfully
   
   

   [root@Linu01 ~]# vgdisplay --- Volume group --- VG Name TCPDumpVolGRP System ID Format lvm2 Metadata Areas 3 Metadata Sequence No 1 VG Access read/write VG Status resizable MAX LV 0 Cur LV 0 Open LV 0 Max PV 0 Cur PV 3 Act PV 3 VG Size 11.91 GB PE Size 32.00 MB Total PE 381 Alloc PE / Size 0 / 0 Free PE / Size 381 / 11.91 GB VG UUID 9fWFIS-vDlg-xOW6-Xmb8-Tkrg-GPZw-ZnUZwh --- Volume group --- VG Name VolGroup00 System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 6 VG Access read/write VG Status resizable MAX LV 0 Cur LV 5 Open LV 5 Max PV 0 Cur PV 1 Act PV 1 VG Size 9.88 GB PE Size 32.00 MB Total PE 316 Alloc PE / Size 316 / 9.88 GB Free PE / Size 0 / 0 VG UUID zz6pnX-TR24-jPcE-zHrv-loz5-TPd2-eERHtq

   
   

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Kartik Suryanarayanan  - Nice LVM artcile. |11/07/2009 04:56:00 HI, It was a nicely written LVM configuration article. For me it was the part , where it was show how to change the PE size used for a VG. Thanks a lot :-) --Kartik S Reply | Quote

thirt |15/07/2009 18:00:58 Hi Kartik, Thanks for the feedback! Keep it coming. If you have any requests, post them in the forums area and we’ll get to them when we get sometime. Regards, Tom Reply | Quote

Wojtek J |17/09/2009 08:08:30 Hello, Same remark as my predecessor. The helpful info was PE size switch "-s". However, the dark colour of the backgrouung is somehow painful ;-) Wojtek Reply | Quote

Anonymous |27/03/2011 23:20:58 plz give information about volume group and physical volumes Reply | Quote

Ajay Sharma  - LINUX tutorial |27/03/2011 23:23:37 plz revert me through my mail Reply | Quote

MD Shamim Akhtar  - Disk /dev/sdb doesn't contain a valid partition t |29/03/2011 01:39:35 Dear Sir, I want to know what does it mean by this line, please make me understand. "Disk /dev/sdb doesn't contain a valid partition table" Reply | Quote

SAS |15/09/2011 01:47:31 It simply means that devices /dev/sdb, /dev/sdc and /dev/sdd don't have any partitions on them _yet_. Partitions are added to the disks in steps 2 and forward. Reply | Quote

Anonymous |02/05/2011 10:48:33 hi Its good Reply | Quote

Anonymous |07/03/2012 01:02:11 nice but the main part is missing Reply | Quote

nelson |31/03/2012 03:18:43 hi, love it, it rally helped me well done well done and well done man. Reply | Quote

hi I'm chanthorn |17/05/2012 20:43:07 U can add more information in this configure . But this configure can accept ok. thanks, Reply | Quote

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