[mythtv-users] boot off compact flash. Recordings & SQL DB on same drive?

Bob spam at homeurl.co.uk
Sun Apr 29 02:03:37 UTC 2007


Stroller wrote:
> Thanks for your reply, Bob.
>   
>>> ...
>>> Because if I need to put / on a separate hard-drive then my  
>>> choices are:
>>> - buy an 80gig hard-drive (the smallest currently available new)
>>> for / and leave it mostly empty
>>> - find an old 20gig - 40gig drive lying around & use that.
>>>
>>> In either of these cases it seems to me that having two hard-drives
>>> running will be noisier than having merely one. An older drive that I
>>> had lying around is likely to be older and particularly noisy!!
>>>
>>> Using a CFcard would therefore seem to reduce noise somewhat. I can
>>> accept having a single hard-drive operating when I am watching TV,
>>> but I would prefer to reduce the number of other components making
>>> noise.
>>>
>>>       
>> I'd do what I suggest in this thread
>> http://www.gossamer-threads.com/lists/mythtv/users/265064#265064
>> put /etc and a few of the more static mount points on a CF card
>> with the rest on a Fujitsu 200GB 4200RPM laptop harddrive.
>> ...
>> if you put /etc and a few of the more static mount points on a CF card
>> with the rest on a Fujitsu 200 you could then use LVM to join  
>> whatever's
>> left of that drive with another, probably resulting in around 390GB of
>> storage for recordings, that consume less than 5w"
>>     
>
> Off the top of my head (it's early here, and I've only just poured my  
> second cup of tea) I take "a few of the more static mount points" to  
> mean everything except /var - logging & MySQL database.
>
> So I've partitioned the 200gig drive into 10gig for those & 190gig  
> for recordings - that leaves the MySQL database on the same drive as  
> recordings. Does this not create a problem?
>
> I'm sure that I had read that accesses to the MySQL database had  
> caused glitches during recording for some people. Is this correct?  
> Does it only apply to HD?
>   

My guess is it'll be fairly hardware and use dependent, I used to have a 
frame grabber capturing to the same harddrive as my  DB with no 
problems, but I had plenty of ram (0.5GB) and the drive had an 8MB 
cache, the motherboard was an ESC K7S5A which had an SIS chipset.

It would probably be useful to have a page on the Wiki detailing who has 
experienced this problem and with what hardware and settings, 
particularly whether write caching was enabled.  In general if you tweak 
your hardware I'd hope you'd be OK, but maybe I've just been lucky, it 
may be worth looking into using ionice to tinker with priorities.

http://www.linuxhelp.net/guides/hdtweak/
http://www.gentoo.org/doc/en/articles/l-afig-p8.xml
http://www.die.net/doc/linux/man/man1/ionice.1.html

-- 
Garrr, do your bit for global warming, become a pirate, you can "borrow" my copy of Windows 95 if you want.



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