Re: best practice for lvm?
On Wed, Jun 03, 2009 at 02:23:27PM -0500, Boyd Stephen Smith Jr. wrote:
> In <[🔎] 20090603185138.GA25966@m364d1.ece.northwestern.edu>, Zhengquan Zhang
> wrote:
> >On Wed, Jun 03, 2009 at 01:46:27PM -0500, Boyd Stephen Smith Jr. wrote:
> >> In <[🔎] 20090603174408.GA25275@m364d1.ece.northwestern.edu>, Zhengquan Zhang
> >>
> >> wrote:
> >> >Can I say the best practice for lvm is to create a single partition for
> >> >the harddrive and single PV on it
> >>
> >> I prefer not to use a partition table at all if I'm using the whole disk
> >> for LVM.
> >
> >I just read this from the lvm howto
> >
> >http://tldp.org/HOWTO/LVM-HOWTO/initdisks.html
> >
> >Not Recommended
> >
> >Using the whole disk as a PV (as opposed to a partition spanning the
> >whole disk) is not recommended because of the management issues it can
> >create. Any other OS that looks at the disk will not recognize the LVM
> >metadata and display the disk as being free, so it is likely it will be
> >overwritten. LVM itself will work fine with whole disk PVs.
>
> This doesn't really apply to me, as I refuse to run MS Windows on my own
> hardware and haven't had occasion to use BSD/Hurd/Mac OS X/OpenSolaris.
I will solely run Linux so it seems to me that using whole disk is fine
to me too.
>
> >could you explain why it is good to use whole disk for lvm?
>
> From what I understand, you might get one extra PE. But, that's all I can
> think of. There's no performance change.
IT is great to have extra space:)
>
> Maybe having a partition table is better, but I don't understand the desire
> for a partition table when it is not really going to the used to partition
> (i.e. divide into parts) the disk.
>
> >> >and separate LVs for /tmp /var /home
> >>
> >> You definitely want separate LVs for any partition (non-system) users
> >> can write to, to avoid running out of space on your / partition. I
> >> usually go overboard and have separate partitions for:
> >> /boot # If / is on LVM; not LV
> >> /usr
> >> /usr/local # For OS migrations.
> >
> >Could you elaborate on this, I'd really like to learn more about your
> >setup. Do you put OS independent stuff in this?
>
> Right now, the only thing I have in there is
> /usr/local/share/doc/susv{1,2,3}. It's documentation I want available to
> any user on the system, but that isn't provided by openSUSE. In the past I
> also put extra xessions in /usr/local/share/xessions and local scripts or
> programs in /usr/local/{s,}bin.
>
> Basically, it is for replacements/extensions/additions to /usr. I reserve
> /usr to the OS package manager.
>
> This allows be to reformat/delete the contents of /usr -- for migrating from
> openSUSE to Debian or vice-versa.
That makes sense.
>
> >> /home
> >> /opt
> >> /srv
> >> /var
> >> /var/tmp # RAID 0 or other "fast"
> >> /var/cache # RAID 0 or other "fast"
> >> /tmp # Usually tmpfs; no LV
> >
> >This setup is intense.
>
> Yeah, as I said, it might be overkill. For my VPSes I just use the setup my
> provider gave me; one large partition for / and one small partition for
> swap. For my laptop, I'm using small partition for /boot, large parititon
> for LV. LVs for /, /usr/local, /home, and swap. /tmp on tmpfs. My desktop
> is the only system that has the "full" layout.
Pretty reasonable to me.
>
> If you have 2G or more of RAM, you will most likely be fine having /tmp on
> tmpfs. You can probably do it on even less RAM.
Thanks a lot for the detailed explanation!
Regards,
--
Zhengquan
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