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Re: Installer: problem installing onto LVM on RAID1




Hi Ron,

On Sun, Apr 09, 2017 at 06:43:32PM +0100, Ron Leach wrote:
> What partitions - I think I mean logical volumes - might I be best
> using for my installation, keeping in mind that I will need to extend
> whatever logical volume houses the 'users-files'?

I think you are making a conceptual error in using the entirety of
your 3TB volume group as a single logical volume (LV) for the root
filesystem.

One of the points of using LVM is that you can resize things later
when you discover more about where the scarcity lies. By allocating
the whole lot on day one, you are forcing yourself into potentially
having to shrink it again later when you want to change something.

If I were you, I'd create several LVs for important filesystems but
start them off pretty small. When they start to get full you can
grow them online.

These days you can have /boot on LVM (or have /boot as part of / and
have that on LVM) and GRUB has no problem booting from it.
Personally, I am old-fashioned; I like booting and the root
filesystem to be simple, so I put /boot and / on separate MD arrays
outside of LVM.

I then have small LVs for interesting filesystems like /var,
/home, /usr/share and application-specific things that I put under
/srv.

Also you can do swap on an LV but as I never need to resize swap, it
is another thing that I tend to keep outside of LVM for simplicity.

> Is using a whole-disk RAID1 a reasonable choice (the kernel raid wiki
> suggests this will work) or would folks on the list recommend
> configuring multiple mds?

Plenty of people would put everything inside one md RAID-1, it is
just personal preference.

The main thing that I think you are doing wrong is fully-allocating
all your volume group on day one, instead of keeping it unallocated
until it is needed.

Cheers,
Andy

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