# LVM / pvcreate vs fdisk / mkfs sector offset.



## O111111O (Aug 27, 2005)

Anybody familiar with LVM? I had a question come up that I can't seem to find answers to.

The issue is creating partitions and filesystems on RAID/SAN based filesystems. When creating a partition with FDISK, a disk header for the partition table is written to the start of a disk. This is done based on BIOS interperation of heads/cyl/sectors of the disk in question. In a RAID the block chunk may need to be offset to compensate for the striping across the RAID in question.

[I.E., to compensate for 63 byte sectors I would offset the start of the partition table by 128. Giving room for the disk header.]

In any case here's my question; Does anybody know if LVM pays attention to this? It seems as if it treats disks in general as raw block devices, so I have difficulty determining if it's reading the disk info from the disk/HBA or from BIOS.

Anybody?


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## saikee (Jun 11, 2004)

I don't use LVM and not qualified to answer your question. However I believe in LVM the disk location appears to be addressed by the label and not as a block device. This arrangement is widely practised by the Red Hat family distros which also like to turn the disks into LVM.

I stay away from LVM because I boot a lot of systems and LVM appears only good for a single distro because it can't even accommodate a single "/boot" inside..


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