[mythtv-users] Raid Performance Tweaking

[Blammo]

On 7/6/06, Debabrata Banerjee <davatar at comcast.net> wrote:
> Whatever you do it's going to be irrelevant for mythtv unless you add a
> massive amount of tuners. Unless you decide to make a RAID array out of 4GB
> disks from 1996.. Even one disk should be good for many streams of video.
> Let's not confuse Mbit and MBytes, as people often do.

Sadly, Debabrata, it's very easily to invalidate that statement.
Here's a couple of examples:

1. Commericial flagging (especially during "Detecting Logo" phase)
2. more than 1 frontend (FFW/REW burn bandwidth)
3. HD Content (alone not bad, but combine with #1 and #2 for single
spindle death)

While your average current disk drive, on sustained SINGLE threaded
reads, sits about 40MB a second, flipping to reads/writes, or 2/3/4
simult reads/writes from different parts of the disk, and now your
throughput on that single spindle is going to be WAY down below that
magical 40MB number, and you will start having performance issues.

As someone who has been through the single spindle, software
raid0/1/5/6 and finally settled on NxHW-Raid5, a single disk is
insufficient for most serious myth setups.