[mythtv-users] Opinion on a P4 Backend // HDD Throughput

[Kevin Kuphal]

On Wed, Mar 5, 2008 at 1:47 PM, Jeff Holicky <myth.myth_user at myth.sent.com>
wrote:

>
> Hi all, I am looking at implementing a Myth system at home - with up to
> five frontends when all is said and done.  We rent a dual tuner PVR and
> also have a cable box - limited to a small harddrive and no real
> archival system nor easy way of playing back multiple formats has helped
> with my decision to create a myth system.  Definitely looking at at
> least 3-4 SD (standard def) tuners initially [PVR 150x4] (later HD) and
> would like some feedback on my initial setup and to realistically set my
> expectations.
>
> Today I want to have the BE act as an occasional FE with plans down the
> road to make it a BE only box (if possible).  Running 100Mbit CAT5 cable
> with the goal to run 1000Mbit CAT6 and/or try wireless.  Perhaps in a
> year or two move to HD by swapping out 2SD tuners.  Start off with two
> dedicated FE's.
>
> Don't want DVD players on each FE - want to stream archive content off a
> NAS device.   (1 or 2TB drive; 100 or Gigabit)
>
> Q1) I am not clear on the ability to do multiple streaming AND recording
> simultaneously.  Someone I spoke to felt my ability to do both may be a
> problem due to bottleneck issues at the HDD.  Assuming a model of 4
> tuners - 1 streaming; 3 recording OR 2 streaming 2 recording; OR 3
> streaming 1 recording -- are all these possible?


For SD recording, I doubt you will run into any issues.  I currently can
perform 2 HD + 2 SD recordings + various commflagging activities + streaming
HD to a remote frontend without any issues on PATA drives.


>
>
> Q2) Then there is that "commercial skipping" process - not sure if that
> still needs to be processed off peak times or not.


You should not have any issue here.


>
>
> Q3) Plus is there a difference between
> a) Streaming program A; recording program B
> OR
> b) Recording program A and streaming program A (few minutes offset)


None that I see will make any difference for your setup.  You can make
efforts to diminish any possible bottlenecks by doing things like:

1.  Storing your logs and database on a disk different than your OS and your
recordings
2.  Using multiple drives configured in a storage group in Myth which will
then spread recordings over multiple drives

>
>
> Q4) I have noticed some that already have 2HD and 2SD tuners in one box
> - but then if they are only recording (on one or more), then there may
> not be any problems.
>
> Q5) My friend suggested the issue was less CPU and more HDD - and maybe
> if I was running a 10K drive - MAYBE I would be okay -- and/or if I
> mixed in a RAID system of sorts to balance the load.


Like I indicated, I have a system with 4 PATA drives on a combination of
internal and PCI IDE controllers doing 2 HD + 2 SD recording + commflag +
watching in progress and I don't see any bottlenecks.  All this is being
done on an Athlon 2000 backend on 100MB networking.

>
>
> Q6) The other thought is adding in a second backend eventually - not
> sure if that is a no brainer or exponentially more complex and not
> desirable.
>
> Q7) I assume playing an archived movie off the NAS is merely networking
> between the NAS and FE - and cabling and less BE - please confirm.
>
> *Config*
> Part of my plan having 4 tuners hit a road block with most MOBOs today
> supporting only 3 PCI cards (Thanks to Brian for pointing that out).  I
> found one so far - but also I remembered I have a P4.  I feel if the P4
> works, based on set expectations, then I can buy a nice higher end
> system as a desktop replacement.  Worse case later turn the P4 into a
> FE.


You should consider the PVR-500 dual tuner to conserve PCI slots.


>
>
> Currently I have:
> - ASUS P4P800 MOBO (enough PCI slots);
> - Intel P4 2.8Ghz w/HT;
> - 2GB RAM;
> - 450W P/S
> - ATI All-in-Blunder 9600 of which I would only use for controlling the
> video out (if possible)
> - ATA 133 HDD - I have several 120GB 7200RPM drives at my disposal ..
> see below
>
> MOBO supports:
>
> - 2xUDMA 100 (4drives)
> - 2xSATA w/RAID 0
>
> RAID CONTROLLER
> - 2xUDMA 133 (4drives)
> - RAID 0, 1, 0+1, RAID JBOD
>
> Moving to SATA doesn't seem to be that much of an option with this MOBO
> - I figure I am just as well with the RAID controller (I use ATA 133
> today with 4 drives).
>
>
> If my ideas of streaming and recording are not far fetched - but my
> config is a little dated, if possible, please point me in a direction -
> need a MOBO that has X; or a minimum CPU Y etc.
> Just want some input - a "that dog will or won't hunt" big picture
> response.
>
> thanks all & cheers!
> jeff
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