[mythtv-users] Partitioning advice request

francis3 francis3 at libero.it
Fri Apr 15 09:37:56 UTC 2011


* Raymond Wagner <raymond at wagnerrp.com> [140411, 20:54]:
[...]
>
>Modern hard drives are quiet. You have more to worry about the fans
>needed to cool a stack of drives, than you do the drives themselves.
>Your bigger issue is likely going to be that P4. The old Netburst chips
>ran hot and slow even when idle. Replacing it with an AMD64 or Core2,
>with a big heatsink and slow fan, will go a lot further than limiting
>hard drive count. A motherboard with a fanless northbridge cooler, and
>a high efficiency heatsink with a 120mm fan will also be noticeable.
>

I'm really picky (maybe obsessesed :-) ) with HTPC noise.
So ... I know what you are talking about.

The MoBo has fanless northbridge cooler, the CPU is an Intel P4 Mobile 
with a thermal junction temperature of 100°C, and very good TDP.
It is cooled by a huge copper heatpipe heatsink with a 120mm low noise
fan,thermally controlled by a DIY PCB with rotational speed controlled
by a thermistore.
The idle CPU temperature, today with room temperature of about 20°C, is
31°C, and after 30 minutes cpuburn test is 47°C 

The power supply is a fanless one. In the system there are only 2 120mm
low noise fans, thermally controlled by independent PCBs.


>> To improve performance the mysql files are stored in a ramdrive.
>
>That is a terrible idea.

Somebody already told me that. :-)

>

[...]

>>
>> Would I get any improvement dedicating a single partition to each
>> tuner?
>
>Getting your root (with database) and swap off the same disk as your
>recordings will go a long way to improving performance.

Do you think that a SSD drive would be a good idea for OS and DB?

 The problem
>with recordings is the disk flush loop in the MythTV file writer. Seven
>digital tuners might manage as much as 20MB/s, and while linear
>throughput of that scale is not a problem on a modern drive, the rapid
>seeking is going to severely reduce the performance. Fragmentation is
>going to make this worse over time, but XFS with pre-allocation should
>help in this area.

XFS partitions are mounted with the following options:
noatime,nodiratime,nosuid,nodev,allocsize=512m 

And I have a cron script which monitors fragmentation and defragments
the drive when there's no activity on the drive.


>A low power 5900rpm drive was a particularly poor
>choice in this regard.

Yes. But, again, I choose the drive with silence in mind. 
What drive would you suggest?

>
>If your single drive does not meet your performance needs, the only
>real
>option is to buy additional hard drives. 

That's what I think I'm going to do.

Thank you for your opinion. Really appreciate it.

regards
f.



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