Mailinglist Archive: opensuse (714 mails)

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Re: [opensuse] small installation help
Haro de Grauw said the following on 10/30/2011 05:17 AM:
Further the option of LVM based, what does it do? I request if someone
could really explain / elaborate/ link me to this (for explanation).

You are not likely to need this unless you are using some advanced
set-up with multiple hard discs. Wikipedia has some decent enough
articles on LVM; it means "logical volume management", and the basic
idea is that you create "virtual" discs which can span across multiple
hard discs. For example, you can combine two 1TB physical discs to
create a 2TB "virtual disc". Or, you can create one 1TB "virtual disc"
that is copied on two physical 1TB discs, so that if one disc is damaged
you don't lose data (this is similar to software RAID, but LVM allows
more flexibility, e.g., combining discs of different sizes).

I use LVM on disks as small as 80G.

LVM mean s you don't have to make decisions about partitioning when you
install. You can be minimalist and adjust the size of the partitions
later.

This might include spreading a partition across more than one disk at a
later date.

LVM also offers things like snapshot backups and striping and easy ways
of doing some RAID-like things.

Forget "virtual". Any FS is just a way to map the management of files
onto disk sectors. LVM gives you greater flexibility.

Tyro asked if he should accept the 'suggested' partitioning offered by
the installer. If he does then he's stuck with it. If he finds he's
devoted too much to "/" and "/tmp" and not enough to "/home" and "/usr"
then he's stuck.

I've installed 11.4 (which was an upgrade from 9.something onwards) on a
80G drive on an older laptop

This is dual boot with Windows, so not all the drive is LVM.
On the Linux side there is a '/boot' and '/' partition.

# df
Filesystem 1K-blocks Used Available Use% Mounted on
rootfs 1035692 549356 433724 56% /
/dev/sda1 171101 77334 84933 48% /boot


# pvscan
PV /dev/sda5 VG vgmain lvm2 [52.73 GiB / 15.27 GiB free]

# lvscan
ACTIVE '/dev/vgmain/usr' [5.91 GiB] inherit
ACTIVE '/dev/vgmain/var' [3.91 GiB] inherit
ACTIVE '/dev/vgmain/home' [3.43 GiB] inherit
ACTIVE '/dev/vgmain/TMP' [1.48 GiB] inherit
ACTIVE '/dev/vgmain/usrshare' [4.00 GiB] inherit
ACTIVE '/dev/vgmain/usrsrc' [484.00 MiB] inherit
ACTIVE '/dev/vgmain/Downloads' [4.01 GiB] inherit
ACTIVE '/dev/vgmain/libruby' [3.00 GiB] inherit
ACTIVE '/dev/vgmain/Thunderbird' [1.68 GiB] inherit
ACTIVE '/dev/vgmain/Documents' [600.00 MiB] inherit
ACTIVE '/dev/vgmain/PDF' [3.00 GiB] inherit
ACTIVE '/dev/vgmain/Ruby' [1.00 GiB] inherit
ACTIVE '/dev/vgmain/Media' [4.00 GiB] inherit
ACTIVE '/dev/vgmain/swap' [1.00 GiB] inherit

It helps to have LVs and hence FSs under 5G so you can back them up onto
a DVD :-)

This machine is used for Ruby development. It is a 33-bt Intel with 1G
of memory.

Of the LVM-based File systems, only /usr/share is above 50% capacity.
That's because I've added many 3rd party 'libraries' for icons and the like.

So

1. No, LVM is not for 'large disks'
2. Yes, LVM lets you defer decisions about space allocation
3. Yes, LVM lets you allocate and reallocate disk space to match your
ACTUAL use as your needs change
4. LVM lets you do striping, mirroring and snapshot backups.
5. LVM lets you use drives of different sizes and technologies to do
the above.

Finally, I've seen no performance hit with LVM. The extra level of
indirection is accommodated in memory, and the issues with file system
efficiency and drive latency are more significant. They are best
addressed by having more memory.

On another machine I'm running 11.4 on a 50G drive (YES!) where almost
everything is NFS mounted (look up PXE) but has 4G of memory. Its a LOT
faster and more responsive than the machine with less memory but more
real local disk.

As far as I'm concerned, LVM is a necessity since I don't know what the
disk-space need will be in the future.

--
Faith: Belief without evidence in what is told by one who speaks
without knowledge, of things without parallel.
--Ambrose Bierce, The Devil's Dictionary
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