Re: [PLUG] Spanning volumes with LVM (Ubuntu)

[Rich Freeman <r-plug@thefreemanclan.net>]

On Sat, Sep 28, 2013 at 5:32 PM, Matt Mossholder <matt@mossholder.com> wrote:
> I would recommend you used the 1TB drive for the OS and DB, and use the
> other two drives for storing recordings. If you want to put other static
> content (pictures, music, etc.) on the recordings drives, that is probably
> OK, as long as you aren't hammering the disks while you are recording.

Honestly, unless you have 10 tuners all running in HD I think this is overkill.

I was running a raid5 across 5 drives containing LVM volumes for OS
and mythtv and was able to sustain recording 4 HD streams at once (on
FIOS, which has fairly high bitrates), along with playback and even
transcoding.  Granted, if I did all that and did something
disk-intensive on the side things would bog down.  Now, this system
had 8GB of RAM, and I had the write cache set to the max 30s, so I'm
sure that helped a bit.

Since then I have moved my OS to a separate drive, but only so that it
can be on an SSD (with hourly rsyncs to an array).  Having the OS on
an SSD certainly confers benefits.

Note that I am talking about multiple drives on a RAID5, which
obviously has benefits when it comes to large sequential read/writes.
LVM across multiple drives really doesn't buy you much except space
unless you're micro-managing your layouts to try to even out accesses.

Rich
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