[mythtv-users] Hard Drive Question

[Robert Denier]

It has been several years since I've run a laptop drive in a desktop 
system, and then only to see if it worked, but if its an ide drive as 
far as I know you simply need a special cable.  Now undoutably ide 
drives either laptop or desktop continue to improve so I suspect a new 
laptop drive would be fast enough.  It looks like the top mpeg2 data 
rate for a 250 card is around 12Mb/sec or 1.5MB/sec.  Now just about any 
drive should handle that these days, but you run into the problem that 
if your are delaying live tv then it has to at least double that + deal 
with all the seeking.

At a quck glance at laptop hard drives on newegg a fujitsu 100GB, 
4200rpm notebook drive runs 193.89 and has a 12ms seek and 8MB buffer.
A 300GB 5400 rpm normal hard drive ( 2MB cache) is $199.  It has a 10ms 
seek time.  (I'd tend to recommend the 8MB cache drives, but this is 
just for comparison.)

As you can see the seek times are close, but the capacities are quite a 
bit different.  Personally I'd think it would work given the numbers 
unless you using  poorly compressed Rtjpeg compression or something.  Is 
100GB enough space for your myth recordings though?  If you needed 2 
drives, you'd pretty much cancel out any savings you might want..  Then 
again you also need to find the adaptor cable for the small drive and a 
way to mount it inside a desktop case.

Personally I doubt its worth it, unless you absolutely need the size.  I 
would look at the power requirements of the 3.5" drives though.  5400 
rpm drives used to use less power than 7200, but I'm not sure if you can 
go by that anymore.  You can also use rounded ide cables or Sata drives 
if your motherboard and linux supports it.  (Getting Sata to work in 
linux might be additional work..)  The main thing is to keep air moving 
in a case..

One other note about a small drive being better cooled.  In order to 
cool correctly the drive needs to be physically mounted to the metal 
housing to transfer at least part of the heat that way.  This would 
likely require a 3.5 inch to 2.5 inch metal adapter.  I haven't even 
looked as to their availability, but I suppose you could make one.  At 
any rate the point being, that you will likely tie up the space 
available whichever drive you use...

If you haven't already found it there is power saving code in the linux 
kernel for various CPU's that run the processor's slower.  (2.6 series 
at least.)  I don't use it, but its more a matter of not taking the time 
to get it working.


David Whyte wrote:

>I think the problem with most laptop drives is they are slow.  They
>run at around 4200rpm to save power.  I don't know if this would be
>considered slow, I think it would, but how it impacts myth, I don't
>know.
>
>Whytey
>
>
>On Mon, 31 Jan 2005 01:13:10 -0500, Maverick <mavantix at gmail.com> wrote:
>  
>
>>Hey all,
>>
>>  I've had a myth box for a couple weeks running KnoppMyth v4r5 and
>>have enjoyed it alot. Unfortunatly, the drive I used is getting more
>>and more bad blocks, and now they're starting to cause kernel panics
>>when mythbackend trys to commercial detect and watch live tv, etc. It
>>was a "bad" drive to begin with, but it's what I had to build myself a
>>proof of concept box. Of course, I fell in love w/ myth and moved all
>>my recordings from my ReplayTV to it. DOH! Anyway...
>>
>>Question is: Can I buy a 2.5" Laptop IDE drive and use it in my
>>(normal desktop) system? I've never used small HD's in non-laptop
>>systems before, anyone have any advice, pages to read, etc? My main
>>motive is sound, and I'm also packed into a small case, so I figure a
>>small HD would be better cooled and much quieter. Is it worth the
>>extra $$ for the small drive?
>>
>>Any experience / suggestions would be greatly appreciated! Thanks!
>>
>>-Kenneth
>>
>>
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>>
>>    
>>
>
>
>  
>
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