Re: lvm on a single big partition or just a single big partition?
On Thu, Jun 04, 2009 at 09:39:42AM -0400, Douglas A. Tutty wrote:
> On Wed, Jun 03, 2009 at 10:04:36PM -0500, Zhengquan Zhang wrote:
> > On Wed, Jun 03, 2009 at 06:48:03PM -0400, Douglas A. Tutty wrote:
> > > On Wed, Jun 03, 2009 at 11:44:00AM -0500, Zhengquan Zhang wrote:
> > > With one big partition, you lose the ability to:
> > >
> > > - have a separate /var (or /var/log) to keep logs from
> > > filling up /
> > >
> > > - have different mount options (e.g. noexec, nodev) on
> > > /home
> > >
> > > - have a separate /home
> > >
> > >
> > > Without LVM, you lose the ability to :
> > >
> > > - resize partitions as needed
> > >
> > > - migrate data from one disk to another, e.g. if a drive
> > > starts misbehaving but you need to keep the system live
> > > rather than reinstalling/restoring.
> >
> > Could you elaborate more on this? As far as migration is concerned, what
> > is the advantage of LVM?
>
> Your system is operating. You start to get either SMART indications
> that the drive is dying or errors (e.g. retries, times-out, etc) in
> syslog. You add a drive to the system at least as big as the failing
> drive. You make it a physical volume for LVM, and add it to the VG of
> the failing drive. You then tell LVM to remove the failing drive from
> the LV. LVM will migrate the data, extent by extent, from the old drive
> to the new drive, all while the system is still active. Its all in the
> LVM-HOWTO (tldp, in the doc-linux-html package).
This is fantastic, I have read the howto but obviously did not notice
this part.
>
> > > Instead of a separate /boot, I often use a separate / (which contains
> > > /boot). In this way, the / partition isn't part of LVM (I make it 500
> > > MB and usually only have under 200 MB used) and can be booted into if
> > > the need arises, with more tools available than within the initrd. Most
> > > of my boxes won't boot a live CD.
> >
> > So I guess for /tmp /var /usr etc you have separate LVs? or else a 500M
> > / should be too small?
>
> I put /tmp on tmpfs, with encrypted swap (so that /tmp ends up encrypted
> also). Yes, /usr (4G) , /var (4-6G, depending ), and /home (encrypted)
> are on separate LVs. Sizes depend on what I'm doing. /usr mostly holds
> instaled packages so 4G is fine for my desktop system.
>
> I also have /var/tmp and /var/local as separate LVs, encrypted. I keep
> my backups in /var/local. KDE keeps lots of otherwise private stuff in
> /var/tmp.
Great setup, Thanks, Doug, so do you how much space(PE) do you leave
unassigned for later use?
>
>
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--
Zhengquan
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