<div class="gmail_quote">On Nov 15, 2007 8:50 AM, Mark J. Small <<a href="mailto:msmall@eastlink.ca">msmall@eastlink.ca</a>> wrote:<br>
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<div class="Wj3C7c">On November 15, 2007, Tom Dexter wrote:<br>> On Nov 15, 2007 5:39 AM, Mark Small <<a href="mailto:msmall@eastlink.ca">msmall@eastlink.ca</a>> wrote:<br>> > In such a system, your biggest bottleneck will likely be bandwidth to the
<br>> > hard disk(s). If you've got 4 folks watching HDTV streams, that's a TON<br>> > of data the gets written and read constantly. Some sort of RAID setup,<br>> > or 1 or more slave backends may be necessary.
<br>> ><br>> > Thy only reason to have a beefy CPU for your setup is transcoding to<br>> > mpeg4 to reduce file size.<br>> ><br>> > Mark<br>><br>> I suppose he might...it's hard to say. I have only one frontend with
<br>> three HD-5500 cards in the backend. I'm able to record three HD shows<br>> at once while watching a fourth previously recorded show from the<br>> frontend...that's a lot of IO. My backend is a Dell 4600 with two 500
<br>> GB Seagate IDE drivers simply using a big vdeo LVW2 volume...and that<br>> actually means the OS partition and even the database is on the same<br>> physical drive as part of that LVM volume...which certainly isn't
<br>> ideal. I've never had any noticeable issues. I'm using ext3, so I<br>> had to turn on slow deletes.<br>><br>> Of course with four cards there's a potential for five programs being<br>> written and/or accessed at once...that could be pushing it.
<br>><br>> As far as CPU, I've checked it out while recording three shows and<br>> watching a recording, and the backend is generally as 1-2%...pretty<br>> much asleep.<br>><br>> Tom<br>> _______________________________________________
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</a><br><br></div></div>I'm not saying that it will be a problem, but when he mentioned 4 frontends<br>watching Live HDTV, meaning 4 huge reads + 4 huge writes, the alarms bells<br>went off that there might be an issue. I think there are folks that have bug
<br>setups like this around. Maybe they will chime in.<br><br>My 3 tuner SD backend has no issues with three tuners go full tilt + some<br>playback using a single recording hard drive. But SD is much smaller than<br>HD.
<br><font color="#888888"><br>Mark<br></font>
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<div><br>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.</div>
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<div>The CPU/Memory that you've described is WAY overkill. This is linux man, not Vista.</div>