[mythtvnz] File System for RAID-5

[James Booth]

Thanks (and sorry, just keep referring to Tim's last email which has the
history in it - thanks everyone!). RAID1 with LVM it is.

 

From: mythtvnz-bounces at lists.linuxnut.co.nz
[mailto:mythtvnz-bounces at lists.linuxnut.co.nz] On Behalf Of Steve Hodge
Sent: Thursday, 18 June 2009 1:31 p.m.
To: MythTV in NZ
Subject: Re: [mythtvnz] File System for RAID-5

 

On Thu, Jun 18, 2009 at 12:57 PM, James Booth <james at booths.net.nz> wrote:

Thanks Steve. RAID1 with LVM will give me what I need, I was just hoping for
RAID 1+0 so I could also get the performance gain, which may be handy if I
end up with three frontends all watching and recording HD at the same time.
If I had three RAID1 arrays as per Tim's email, and then put RAID0 over the
top, could I subsequently add in another RAID1 pair as per Tim's directions,
and then grow the RAID0 across the extra RAID1 pair without having to
backup? I guess in short I'm asking can you currently add disks/partitions
to a RAID0 automatically without loss of data? I find many conflicting
answers on the net.

I wouldn't worry too much about the performance - hard drives are at least
an order of magnitude faster than HD streams. I believe TV3 runs around
11Mbps, a modern drive will easily handle in excess of 400Mbps. A two disk
RAID1 should be capable of nearly twice the single disk read speed - when
you've got multiple reads going (as its the case with streaming three files
to different frontends) RAID1 should be approximately the same speed as
RAID0 for the same number of drives.

As far as I know you can't extend RAID0 arrays with mdadm either (at least
the man page says 1/4/5/6 only). My advice is that if you're really
expecting to extend the array any time soon just buy the drive now.

By the way, that stuff you keep referring to from Tim's email was also
written by me :-)

Cheers,
Steve

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