[CentOS] LVM hatred, was Re: /boot on a separate partition?

Thu Jun 25 15:50:57 UTC 2015
Robert Heller <heller at deepsoft.com>

At Thu, 25 Jun 2015 11:03:18 -0400 CentOS mailing list <centos at centos.org> wrote:

> On Wed, June 24, 2015 16:11, Chuck Campbell wrote:
> >
> > Is there an easy to follow "howto" for normal LVM administration
> > tasks. I get tired of googling every-time I have to do something
> > I don't remember how to do regarding LVM, so I usually just
> > don't bother with it at all.
> >
> > I believe it has some benefit for my use cases, but I've been
> > reticent to use it, since the last time I got LVM problems, I
> > lost everything on the volume, and had to restore from backups
> > anyway. I suspect I shot myself in the foot, but I
> > still don't know for sure.
> >
> At the risk of some ridicule I suggest that you look at installing
> Webmin.  It is a web based system administration tool that I find
> invaluable.  The two most common complaints I encounter when I discuss
> its merits are 'security' and 'transparency'.
> The security issue is trivially dealt with. Install Webmin and
> configure it to listen on using its standard port TCP10000. 
> Install Firefox on the same host and then run firefox from an 'ssh -Y'
> session using the --noremote option.  If you are totally paranoid then
> firewall TCP10000 as well, configure Webmin to use https only, and
> then only start the webmin service when you are performing
> maintenance.
> There are less draconian measures that are in my opinion equally
> secure from a practical standpoint but I am sure that you can figure
> those out on your own.
> The transparency issue is really unanswerable.  There exists a school
> of thought that if you are going to administer a Linux system (or OS
> of the proponent's choice) then you should learn the command syntax of
> every command that you are called upon to use.  This is the
> one-and-only path to enlightenment.  Like upholding motherhood and
> promoting the wholesomeness of apple-pie this sort of moralizing
> really brooks no answer. You can guess my opinion on that line of
> puritanism.

HA!  You only really need to learn *one* command: the man command.  The man 
provides 'enlightenment' for all other commands:

man vgdisplay
man lvdisplay
man lvcreate
man lvextend
man lvresize
man lvreduce
man lvremove
man e2fsck
man resize2fs

These are the only LVM commands I use regularly (yes there a a pile more, but
most are rarely used and a handful only used in startup/shutdown scripts or
when rescuing) and I often end up use the man command to refresh my memory of
the command options. 

> As you have painfully discovered, infrequently used utilities and
> commands are difficult to deal with.  The process of learning, or
> relearning, the correct arcana is particularly noisome given the
> notorious inconsistency of syntaxes across different utilities and the
> spotty coverage of up-to-date documentation.  Google can be a
> dangerous guide given the wide variation of practice across differing
> flavours of *nix and the widespread aversion to providing dates on
> writings. In consequence I consign transparency arguments and their
> proponents to the religious fanatic file.  Nothing personal but there
> is no point in arguing belief systems.

Right, expecting a *web search* to give *correct* command documentation is 
problematical.  Using the local system man pages often works better, since the 
man pages installed with the installed utilities will cover the *installed* 
version and not the version that might be installed on a *different* distro, 

> If you want to get infrequently performed sysadmin tasks done reliably
> and with a minimum of fuss use something like Webmin and get on with
> the rest of your life.

Robert Heller             -- 978-544-6933
Deepwoods Software        -- Custom Software Services
http://www.deepsoft.com/  -- Linux Administration Services
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