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LVM or no?
spielentwickler 
5/9/08 1:29:25 AM
Guru

So, I'm still setting up this new box, and I've got a bit of a choice to make.

Currently, my partition table looks like this:
 
Device Boot Start End Blocks Id System
/dev/sda1 * 1 2611 20972826 7 HPFS/NTFS
/dev/sda2 2612 2617 48195 83 Linux
/dev/sda3 2618 7298 37600132+ 5 Extended
/dev/sda4 7299 14593 58597087+ 8e Linux LVM
/dev/sda5 2618 2741 995998+ 82 Linux swap / Solaris
/dev/sda6 2742 7298 36604071 83 Linux


sda1 is Windows, sda2 is /boot, sda5 is swap space and sda6 is /

It's sda4 I want to talk about. Now, the plan is to have a large partition for use with recording digital tv when it's booted in MythTV mode. At the moment it's got about 60GB there.

Eventually, I plan on sticking a second hdd in here, probably a 500GB or 1TB job.

I want to be able to add some of that space to that partition. There's two ways I can go about it, I think.

1) Use the hardware sata raid to raid0 it with my current hdd, then I could just extend the partition itself onto the new hdd, without having to worry about LVM. Would LVM make this easier though?

2) Set up the drives seperately, and use LVM to add a parition (or several) from the new hdd to the same volume as this partition on the current drive.

The benefits, to my understanding, of the first method is that I may not have to use LVM. Linux will just see one block device, and I can just extend the partition into the new space. That's partly the reason why I stuck that partition at the end of the current drive.

However, I have heard LVM makes it easier to manage size changes and such, and so if I set up LVM now, even with only one partition, later I can just add other partitions to the volume.

So, what say you atomic, which would you do?

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iamthemaxx 
5/9/08 9:21:47 AM
Mod
SuperHero

Immortal


1) Spuh?
You can't create a RAID array onto a new drive with an existing drive without blowing what is already on the disks away. At least you can't on consumer level controllers.

2) Won't work.
The issue is that unless you already have LVM setup, you won't be able to add space from the new disk to the old disk. You can only extended new LVM volumes on to other existing LVM volumes, not from LVM to normal disk partitions.


I am not sure if software RAID could do what you want, but it looks like you will need to either rebuild your disk structure, or have a mixture of LVM and normal partitions, or just use all normal partitions.

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spielentwickler 
5/9/08 9:30:41 AM
Guru

thanks, I can see why the first option is not likely to work, but i think you missed the point of my second option.

In the second one, I set up several partitions on the new hdd to be used as lvm volumes, then add them to the original volume.

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iamthemaxx 
5/9/08 9:32:46 AM
Mod
SuperHero

Immortal


Yeah I get you.

But you can't add LVM partitions to the existing disk, unless they are logical volumes themselves (which they don't look like - /dev/hda1)..

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spielentwickler 
5/9/08 10:07:36 AM
Guru

/dev/sda4 on the current disk is set aside as an lvm partition.

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iamthemaxx 
5/9/08 11:17:13 AM
Mod
SuperHero

Immortal


Ahh, in that case it should be ok to extend it.
Quite easy.

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