[GRLUG] Raid, LVM, and Cheap Storage

[Adam Tauno Williams]

On Tue, 2008-10-14 at 14:01 -0400, Ben DeMott wrote:
> How long does it take to transfer the state of 39VM's ? (and yes I
> understand this may be through ISCSI)

No idea, wasn't my box.  Was just talking to some guys about ESX.  In
his case the disks were local which probably helped (hence the 3U box).
That would be a pretty big hit to iSCSI (unless you've got 10GE already
[one can dream]).

> I remember having 6 VM's on a pretty beefy Proliant with bunches of
> memory, and the IT manager kept moving my VM's off to older servers, 6
> VM's in one place was just too much for his brian to handle I guess.

:)

> Thanks for your response Adam, 
> >> In Linux this is furthered by the fact we have LVM2 and Software
> Raid
> >> support in our Kernels.
> >Every other current OS provides these as well.
> Really ? What does Windows Server 2003 offer at the kernel level
> similar to the capabilites of LVM2?

The Dynamic Volume support in Windows LDM is very much equivalent to LVM
in UNIX.  DVs can be migrated, extended, reduced, and span multiple
physical volumes.  By default LDM creates "Basic" volumes which do *not*
have these features (much like setting up a LINUX distro with disk
partitions instead of LVM).

> My comment was more or less for smaller - medium shops who aren't
> willing to make the real investment and see Virtualization as a
> 'savior'. 

Sure, but we used MD and LVM prior to virtualization.  Virtualization
makes the issues easier to deal with (more flexibility) but it doesn't
fundamentally change any of the issues.   The real problem with
pre-virtualization storage [DASD] is that it is just never in the right
place.

>  How many people in IT know what you know and can support what you can
> support?

Lots.

> I run into a lot of people, and I haven't meant very many that off the
> shelf know much more about ESX other than what the manual told them.

Well, that would include me.  I've had no ESX training.  The manual is
pretty good. :)  And none of this is rocket-science.  Any reasonably
literate person with well developed abstract reasoning skills can figure
this stuff out.  Emphasis on the "abstract reasoning skills";  but in
the 21st century people who can only think in the concrete are just
epically screwed.

> Small/Medium Shops make that initial leap, then don't have the
> knowledge, expertise, or budget to retain, pay, or hire individuals
> who can manage the complexity - the technology itself. 

Ok, but that is the purpose of bankruptcy.  Not all the salmon make it
upstream.  And the great majority of small businesses fail.  Kudos to
the consultant that managed to get the coin out of their doomed hands
before they went under.

> And I did qualify my statement, "You need to backup your data on
> another storage array if you are going to do this, preferably not
> abstracted by a virtual file system, then the combination above is a
> great solution."

Agree.  I think that is the root of the quote:
"There are two things that you need to know about storage. The first
is that it keeps getting cheaper---unbelievably so.  The second is that
it keeps getting more expensive---unbelievably so."
--- The Practice of System and Network Administration

Cheap storage is a siren song;  cheap to get and then dangerous if not
managed correctly, and the management of storage is far more expensive
then the up-front cost.  Many things in life work that way,  hence the
emphasis on thinking in terms of TCO and not "price".

> >These questions are all part of creating a *legally required* data
> >retention policy.  Acting contrary to an organizations data retention
> >policy opens the possibility of *criminal* prosecution.  The fear of
> >lawyers is very effective in making an organization get pro-active
> >about such things.
> ><http://www.whitemiceconsulting.com/node/157>
> I couldn't agree more!
> What a nice world you must live in, where companies are concerned with
> legality and processes :)

If your employer doesn't care you need to quit.  If your customers (as a
consultant) don't care you don't need those kinds of customers.  

One thing to remember is that the BSA and some other organizations offer
bounties for reporting piracy, etc... I'd wager if your employer doesn't
care about data-retention, etc... that they have unlicensed software too
- so you can walk out the door and collect a nice parachute. :)

Fortunately the IT job market is pretty hot.