[mythtv-users] Storage Questions. LVM, RAID, NFS

[Steven Adeff]

On 5/2/06, chris at cpr.homelinux.net <chris at cpr.homelinux.net> wrote:
> On Mon, May 01, 2006 at 03:06:33PM -0500, Dean Wilson wrote:
> > As I understand it from these discussions, Raid5 requires 5 drives, 4
> > of which will be used for storage?  (So 5 250GB drives would sum to
> > 1TB of useable HD space?)
>
> RAID 5 works with 3 or more drives.  I'm using 3x160Gb to get 320Gb
> of storage.  Using more drives results in less wasted space but
> increases the risk of a dual failure.  Most HOWTO type sites suggest
> that once you get to 6 or more drives you should use RAID 6 instead.

Some notes of personal experience and a question,
I have a 3 disk raid5 array and its not quite fast enough for my 3xHD
tuners+1xPVR150+1xFirewire Cablebox (though I plan on dropping the
firewire box). I'm converting over to a 4 disk RAID10, hoping it will
be fast enough... I hate losing two disks to mirroring, but it will be
faster than a 4 disk RAID5 array and speed is my issue now not drive
space (I'll have 2 other RAID5 arrays for archival, one made of
3x250GB drives and another of 4x320GB drives).

Would a 4 disk RAID10 be better than RAID5 for a recordings drive
considering I may have times where I've got my 3x HD recorders and my
PVR150, (possibly swaping for a PVR500) plus having at most 2x HD
capable frontends running?

Also, if you go with XFS for your file system, which I've been using,
I highly recommend running a nightly cron job of "xfs_fsr". This will
go through each of your XFS mounted drives and "defrag" them. I wasn't
doing this and have found my recordings drive has gotten quite
fragmented causing a noticable difference in transfer speed.

--
Steve
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