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s2cuts 01-12-2008 08:19 PM

Setting up LVM with full disks...
 
Hi all,

I'm new to LVM, and am wondering if it's possible to initialize partitions with data on them as physical volumes, assign them to a volume group, then make a logical volume that covers all the physical volumes, and be able to mount it and still see all the data? (I know, run-on sentence) You can probably see my dilemma. Is there any other way to implement LVM without having to do mass data transfers?

Also, being new to LVM, I'm trying to understand if there would ever be a case that would require you to create multiple volume groups? I mean doesn't it make more sense to just create multiple logical volumes instead? BTW, I'm just running a home file/ftp server with multiple disks.

Thanks for any help or advice,
s2

MensaWater 01-13-2008 09:26 AM

You can't convert a live partition/disk to an LVM "physical volume" (PV) without overwriting it so you'd need to save off the data first.

The reason for multiple Volume Groups (VGs) would be more apparent on large systems with external storage (SAN or NAS) attached. In commercial operations often you allocate a certain amount of storage to a certain environment. In such a case it makes things easier to manage if you create a new volume group for each environment then allocate your logical volumes (LVs) for that environment within the specific VG. This lets you now when you're running out of space for that environment rather than risking running out of space for all environments at the same time.

Also there is a limit to the number of PVs and LVs that can be contained within a single VG so in large commercial operations where you have many environments and the need for many PVs and LVs you often would need to create the separate VGs just to be sure you didn't hit these limits.

s2cuts 01-13-2008 11:27 AM

Many thanks.


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