[mythtv-users] Recording directly to RAID

Marc Tousignant myrdhn at gmail.com
Sun Jul 29 03:07:12 UTC 2012

-----Original Message-----
From: mythtv-users-bounces at mythtv.org
[mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Jean-Yves Avenard
Sent: Saturday, July 28, 2012 10:44 PM
To: Discussion about MythTV
Subject: Re: [mythtv-users] Recording directly to RAID


On 28 July 2012 15:11, Tapani Tarvainen <mythtv at tapanitarvainen.fi> wrote:
> Yes. (With Linux mdadm, RAID10, period. With hardware RAID, it 
> depends.) In particular, RAID5 and RAID6 are poor choices for any 
> situation where write speed is critical (and even RAID10 needs 
> non-default parameters to do well).

I always find it particularly amusing reading about the use of extremes

I doubt Myth will ever require "critical" write speed.

So say you're recording 10 streams at the maximum bitrates of 22Mbit/s,
220Mbit/s is a figure that will unlikely ever see, as a typical DVB stream
is more around 15Mbit/s for some HD channels, and that's if you're lucky....

RAID5 is perfectly suitable for home use, no point disregarding with
statement like RAID10 "period".

The most I've ever recorded at once was 6 streams, most of them SD so
6-7Mbit/s, my RAID5 array with green drives had no issue handling it,
recordings were just fine.

RAID10 is a waste of disk space IMHO if all you're after is disk redundancy
and big storage capacity.

We're not talking about enterprise-class SQL server here...

What next? so only RAID10 SSD disks should be used otherwise everything is
too slow "period" ?

LOL. I always love when this gets brought up.
My server has 2 mirrored OS drives (mdadm), and 4 drives in RAID5 (LSI
Controller w/ battery) for media storage.
I have 7 potential HD capture sources, 3 of which could be multi captures
due to multiplex sharing. Never have I come close to maxing out the write
performance on the drives. I actually just decided to shutdown 3 of my
sources because I haven't been coming close to needing them all.


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