[NCLUG] sw raid, recovery after install

Bob Proulx bob at proulx.com
Wed Jan 23 00:48:03 MST 2013


Sean Reifschneider wrote:
> Bob Proulx wrote:
> > I think you might be running into the problem of just having a huge
> > amount of data to move.  Disks have been getting larger faster than
> 
> Yeah, but that 120 hour verify time is certainly a lot of seeks for small
> amounts of data, basically a large database job on the file-system
> meta-data.

Wow.  120 hours!

> I'm really conflicted about hardware RAID.  Most of the controllers are
> proprietary, so if you have an issue and need to try to get data off you
> often can't figure out the on-disc layout without reverse-engineering it.

Agreed.  It really only works if you have a large number of exactly
the same controller cards available to you.  For a one-off
installation it is terrible because then you won't have other systems
available to use to recover the data.  Give me software raid every
time then.  But in a datacenter filled with the same type of
controller everywhere like at HP then it is okay.

> > It is probably ten minutes or so for me from install to finish.  It
> > really depends upon how large of a system I am installing.  The
> > desktop can take ten minutes just by itself.  But I never install a
> > desktop on a server machine.
> 
> True.  I really don't put RAID on a desktop...

And that is even harder in a laptop.  Not impossible.  Just harder.
And no longer important now that SSDs are available.

I never used to use raid on my desktop.  But then drives became
inexpensive and now my desktop is a raid machine.  Why not?

> If I were to get annoyed about anything wasting my time on Ubuntu or
> Debian it would be that the installer is such an attention-whore.

Only the disk partitioner is really attention intensive.  Everything
else I can fly through very quickly without much thought.  I only use
the keyboard and never the mouse.  That is the Debian installer.  I
think Ubuntu calls it the alternate installer.  I don't like the mouse
isntaller.  With the keyboard installer are really only three keys
used during the install.  Up, down, enter.  I am very fast with it.

But the disk partitioner for a raid and lvm installation takes me a
couple of minutes to work through while all of the while hitting keys
up, down, select, repeatedly as I work through the setup with I bet no
longer than one second pause between keys hit.

> Unless you have the pre-seeds set up, it will do some of the
> install, ask the human for some questions, do some more install, ask
> more questions.  That drives me nuts!

Well...  It is quite modular.  So it doesn't really know what all of
the questions it wants to ask until it gets to that part.

I do have all of the preseeds set up for hands-off installations too.
But only for simple client machines.  I have automated the
installation with a PXE network boot menu.  Boot off the network.
Select the system you want to install, 32-bit, 64-bit, some other
different configurations.  It asks you for a hostname.  Then from
there it is fully automatic and will eventually reboot to a login
prompt and it is done.  In particular this is nice at the school so
that they can image client desktop machines whenever they get new
hardware to set up.

> The newer Ubuntu desktop installer that is doing install tasks while it
> asks you questions is nice.

I haven't played with it yet.  I tried booting the latest Ubuntu in a
KVM recently and for whatever reason it would hang during the
installation.  I didn't feel like installing it on real hardware yet
and was just wanting to play in a VM.  And so I haven't yet been able
to drive it around it yet.

> We mentioned you the other night when some folks were talking about Buddy
> Holly and The Big Bopper and their plane getting struck by lightning and
> how likely that was, figured you'd know the stats off the top of your head.
> :-)

I have never been hit by lightning!  I try to stay away from
thunderstorms.  They are bigger than I am.  But most reports about
lightning strings in aluminum aircraft are that they are a non-event.
Nothing significant happens.  (Composite aircraft are new and as yet
still somewhat unknown.)  A quick web search says airliners get hit
1-2 times per year per airplane.

I am much more worried about hail.  Hail can really damage an
airplane.  And you can't really just stop and hang out under an
overpass if you get caught in it.

Airplanes fly in the rain just fine however.  It can be quite loud
though.  Sometimes so loud you can't hear the intercom or radio even
with the headset.

Bob



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