[mythtv-users] My First MythTV Box

David Brodbeck gull at gull.us
Tue Jan 1 00:11:34 UTC 2008

On Dec 31, 2007, at 4:02 PM, Don Jerman wrote:

> On 12/31/07, Mike Perkins <mikep at randomtraveller.org.uk> wrote:
>> match at ece.utah.edu wrote:
>> It is an *extremely* sensible idea to separate your system files  
>> and your Mythtv
>> files onto separate disks. *Especially* to put the Mysql database  
>> on a separate
>> disk to the video storage. When recording there are many I/Os to  
>> the video disk
>> at the same time as many I/Os to the Mysql database. You really  
>> don't want to be
>> thrashing your heads from one file to another at the rate video  
>> comes in.

> I tend to value the bays more.  I would agree if they were IDE drives,
> but this board supports SATA-II, and you should use it.  3Gbps = about
> 22GB/hr, HD streams are about 7GB/hr so you can play 1 and record 2
> and have change left over for mysql and mythweb - on a single SATA
> channel.  Of course if you plan to work it harder than that, you
> probably need more drives and channels anyhow.

It's not so much the bandwidth, it's having to slew the heads back and  
forth from file to file.  You won't get anywhere near 22 GB/hr total  
when you figure in the latency of moving the heads around.  If you  
have lots of spare RAM the disk cache will help with this, of course.

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