[mythtv-users] how much is enough -- configuring a server
Sean Goodpasture
goofygrin at gmail.com
Thu Nov 15 18:54:36 UTC 2007
On Nov 15, 2007 8:50 AM, Mark J. Small <msmall at eastlink.ca> wrote:
> On November 15, 2007, Tom Dexter wrote:
> > On Nov 15, 2007 5:39 AM, Mark Small <msmall at eastlink.ca> wrote:
> > > In such a system, your biggest bottleneck will likely be bandwidth to
> the
> > > hard disk(s). If you've got 4 folks watching HDTV streams, that's a
> TON
> > > of data the gets written and read constantly. Some sort of RAID
> setup,
> > > or 1 or more slave backends may be necessary.
> > >
> > > Thy only reason to have a beefy CPU for your setup is transcoding to
> > > mpeg4 to reduce file size.
> > >
> > > Mark
> >
> > I suppose he might...it's hard to say. I have only one frontend with
> > three HD-5500 cards in the backend. I'm able to record three HD shows
> > at once while watching a fourth previously recorded show from the
> > frontend...that's a lot of IO. My backend is a Dell 4600 with two 500
> > GB Seagate IDE drivers simply using a big vdeo LVW2 volume...and that
> > actually means the OS partition and even the database is on the same
> > physical drive as part of that LVM volume...which certainly isn't
> > ideal. I've never had any noticeable issues. I'm using ext3, so I
> > had to turn on slow deletes.
> >
> > Of course with four cards there's a potential for five programs being
> > written and/or accessed at once...that could be pushing it.
> >
> > As far as CPU, I've checked it out while recording three shows and
> > watching a recording, and the backend is generally as 1-2%...pretty
> > much asleep.
> >
> > Tom
> > _______________________________________________
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>
> I'm not saying that it will be a problem, but when he mentioned 4
> frontends
> watching Live HDTV, meaning 4 huge reads + 4 huge writes, the alarms bells
> went off that there might be an issue. I think there are folks that have
> bug
> setups like this around. Maybe they will chime in.
>
> My 3 tuner SD backend has no issues with three tuners go full tilt + some
> playback using a single recording hard drive. But SD is much smaller than
> HD.
>
> Mark
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>
Disk and network IO will be the bottleneck. You'll need Gig-E. Considering
that raids typically slow down writes and speed up reads, you'll probably
want to investigate a raid for the storage.
The CPU/Memory that you've described is WAY overkill. This is linux man,
not Vista.
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