[mythtv-users] Should I use LVM on this new raid?

[Joe Ripley]

On 9/21/07, Brian Foddy <bfoddy at visi.com> wrote:
> Building a new mammoth backend server.  It has a
> 3ware 9650 8port raid card, and I'm starting out with
> 2 x 1000GB HDs, initially I plan them in raid0.  As
> the budget will allow I'll probably add a couple more
> and go to raid5.  I won't guess how many total drives
> it might grow to, probably 4-5 in a raid5 setup.  And
> starting with 1000GB drives pretty much locks me into
> that size forever.

The 3ware card is a good choice as far as I know.  It supposedly has
very good Linux support, so you should never have a problem
integrating it... its also a true RAID card, as opposed to other
(cheaper Promise cards, et. al.)

As for growing the RAID from 0 to 5, I know this is supported on some
hardware (HP comes to mind).  It's not supported using Linux software
RAID (yet).  I think that 3ware has a config utility that might let
you do this.

> As I get acquainted with the raid card, it has pretty
> easy support for adding  new drives to the raid without
> reformatting.

Well then, I guess expanding is supported with 3ware. :)

> In addition to the videos, the raid will also hold other
> bulky backups, mirrors of internet dirs, and other misc
> storage as needed, but predominately video.
>
> Would people suggest I add LVM software on top of this,
> or will I have enough flexibility with just the raid?  Also,
> I've normally used XFS, but with LVM the inability to
> shrink a filesystem gives me pause about using it.
> I've always had good luck with XFS tho, and really like its
> deletion speed.  Question to myself, would I ever need to
> shrink the video filesystem?

I don't have much experience with LVM, but XFS is probably the best
choice when creating a large array.  It can handle huge file systems
and has functions that take advantage of RAID properties (like stripe
size).  Although, I think that by setting certain values, an XFS file
system might have an upper limit on its maximum size... not sure about
that one (I know it can support huge sizes).

Anyway, if its a new array, play around with some different scenarios
to see which gives you the best bang for your buck.  By testing
different settings you can figure out which provides the best
performance.... and then you can share your findings with us. :)

Enjoy!

-- 
Joe Ripley
vitaminjoe at gmail.com