[mythtv-users] mythtv-users Digest, Vol 56, Issue 71

[Kevin Nelson]

On Nov 15, 2007, at 8:19 PM, mythtv-users-request at mythtv.org wrote:

> Chris Ribe wrote:
>> On Nov 15, 2007 9:50 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.
>>
>> While I won't argue that I/O is a potential issue, it not THAT big  
>> of an
>> issue.  4 HD streams only amount to about 7MB/s of data.   If you  
>> have 4 HD
>> tuners, you'll probably want more than one disk for storage, but  
>> you could
>> get by with a  single SATA  disk.
>>
>> -chris
>>
>
> I don't know where everyone got this number of 4 streams.  The OP said
> he was going to have 8 clients and 4 tuners.  That give a possible
> maximum of 12 streams of data (+ 4 depending on how he sets up
> commercial flagging).  Disk I/O will be his major concern. And it's  
> not
> total sustained throughput that will be the issue, it'll be all the
> constant seeking that will be the issue...
>
>   - Wade



Hi everybody, thanks for all of the responses.

It's clear to me now that I should have mentioned that I am looking  
at the ASUS P5E motherboard with as many SATA hard drives as i can  
fit into the case.

The mobo only supports 6 SATA connections, so i'm guessing that I can  
only have 6 drives in a RAID configuration via the mobo's native RAID  
hardware. Since I am planning on using a Chenbro 3U chassis that has  
8 drive bays, I would like to be able to support up to 8 drives in  
RAID, so an external card might be necessary.

My conclusion based on your input is that with this many drives (and  
the seek time distributed appropriately, a Core2 processor will be  
powerful enough to accomplish the task at hand.

Of course, recommendations on a RAID controller or a mobo that  
supports 8 SATA drives and is linux / core2 compatible would also be  
appreciated,

To clarify -- Wade is correct in assuming that the server will be  
dealing with a maximum of 12 streams rather than 4 or 8. Each TV  
might be viewing some recorded program (8 streams) while 4 separate  
live broadcasts are being recorded. This is a circumstance that the  
server must be able to accommodate frequently and efficiently.  
(honestly, i'm not sure if my client will frequently use that much  
power often, but i am certain he'll push it to that limit at least  
once).

Thanks again, as you all have been profoundly helpful.
-kevin
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