Re: [gentoo-user] LVM: Pro and Contra ?

[Meino Christian Cramer]

From: "Richard Fish" <bigfish@××××××××××.org>
Subject: Re: [gentoo-user] LVM: Pro and Contra ?
Date: Tue, 8 Aug 2006 10:59:02 -0700

> On 8/8/06, Meino Christian Cramer <Meino.Cramer@×××.de> wrote:
> >  What's about fragmentation of data, when using LVM ?
>
> There are very few disadvantages.  If you put root on LVM, then you
> will require an initramfs to boot, and as kashani said, if the LVM
> packages break somehow, you will be back to a livecd.  However, I
> think keeping a backup initramfs and kernel in /boot should be
> sufficient for most cases.
>
> The biggest advantage is that you can easily add more space to a
> volume group if you run out.  So say you only allocate the 80G you are
> currently using to your logical volumes initially, you can add space
> to them as required from the unallocated space.
>
> LVM has no effect on fragmentation however, other than that you can
> easily use more and smaller filesystems to keep the effects of
> fragmentation managable.  When you consider how the different areas of
> a gentoo directory tree are used, it makes sense to use different
> filesystems for /, /var, /usr/portage, and /home.  I also recommend
> separate filesystems for /usr/portage/packages and distfiles, just to
> keep those large archives out of the same filesystem that contains the
> ebuilds.
>
> -Richard
> --
> gentoo-user@g.o mailing list
>

Hi Richard !

 Thanks a lot for your explanations! :) 

 Yes, the variable size of a LVM was that feature what attracts my
 attention first.

 Another question came up in my mind: Is a logical volumes (that
 "beast" where I put the filesystem on finally) behaviour identical to
 that of an ordinary old fashioned partion?

 Is it possible (for example) to feed such an lv again through the
 device mapper for encryption purposes ?

 Is the performance impact via LVM (not encryption) noticeable or
 negliable? 

 Keep hacking!
 mcc

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