[SLL] trouble with LVM?

[Bill Campbell]

On Thu, Jan 25, 2007, Glenn Stone wrote:
>On Thu, Jan 25, 2007 at 10:42:58AM -0800, Phil Mocek wrote:
>>On Thu, Jan 25, 2007 at 10:24:19AM -0800, Chuck Wolber wrote:
>>> I've said it before and I'll say it again, distribution
>>> developers are doing end users a grave disservice by making it
>>> so easy to install an OS over LVM. 
>>
>>Do you think it would be more accurate to say, "distribution
>>developers are doing end users a grave disservice by making it so
>>easy to install an OS over LVM *with multiple disks*"?
>
>Honestly?  I think even single-disk LVM systems are problematic.  A lot of
>rescue disks don't know what to do with LVM, and they tend to be more
>squirrely than your average robust ext3-only implementation.  
>
>If I was setting up what ought to be the default, I would say: just to be
>safe, 100mb /boot, as far forward on the disk as you can get (and if it's
>over Cylinder 1024, rant rave raise red flags unless you can figure a way to
>ask the BIOS if it supports more); 10GB / (with option for less on smaller
>disk, down to ~500mb for server-only Debianesque installs); rest of disk
>/home.  All primary partitions.  Boom.  Dead easy, dead simple.  

We stopped setting up a separate /boot partition a couple of
years ago when grub became happy to deal with booting over
cylinder 1024, largely because I find it causes far fewer
problems when installing OS updates or alternate versions of
Linux in its own ``/'' partition.  I don't trust vendor's
installation procedures not to totally screw up things in a
central /boot in these cases, particularly after I've carefully
crafted my grub menu.lst file.

Our ``/'' partitions are now all ext3 as this has proven to me
the most robust of all the file systems available (Glenn
convinced me of this :-).

>>I started using LVM on single-disk systems essentially as an
>>improvement upon using a bunch of partitions.
>
>It *can* be... if (a) you know what you're doing and (b) it doesn't go
>sideways on you anyway.  Me, I just keep the structure simple and reduce
>complexity wherever I can.

I generally stay away from LVM, vinum under FreeBSD, and similar
schemes for general use as they tend to be ``putting all your
eggs in one basket''.

The first time I used LVM was on a ThinkPad 600 laptop that
oringally had something like Caldera OpenLinux 2.2 where 2GB
partitions seemed to allow lots of room for expansion.  At a
later date, I needed a 4gb partition, didn't feel safe messing
with fdisk to remove or resize partitions, so used LVM to combine
two 2GB partitions.  I never have anything on a laptop that is at
all critical that isn't regularly backed up to a server so losing
data isn't a critical consideration.

It seems to me that the place where logical volume managers can
be very useful are in large enterprise operations where storage
is on highly reliable media, and one needs to allocate partitions
for different applications, or do things like provide a logical
partition for every user, restricting the user's ability to do
nasties like fill up the system's partitions.  The first place I
ran into this type of system was one running IBM's AIX at a
fairly large site.  It was very nice to be able to provide
expanded storage for an application without having to go through
major hassle.

Bill
--
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