[mythtv-users] Question re: available SATA ports and linux software RAID

Alex Butcher mythlist at assursys.co.uk
Thu Apr 7 10:47:29 UTC 2011

On Thu, 7 Apr 2011, Jean-Yves Avenard wrote:

> On 7 April 2011 19:33, Alex Butcher <mythlist at assursys.co.uk> wrote:
>> Personally, my view is that with the price of storage as it is, parity RAID
>> is only useful when one needs lots of cheap storage and the data stored on
>> it is mostly quiescent; archives and the like. Otherwise, I prefer either
>> RAID1 or RAID10, depending on budget. Mine is probably a minority opinion,
>> though.
> What a weird view.. So you use RAID1 no matter what? forget about
> wasting that much disk ?

A WD 2TB Caviar Black is £114. I paid over double that for 1.3GB back in
1995, and about 4 times that for 120MB back in 1993.  I've been using RAID
in my home systems since 2002, when 80GB drives were £80 (though back then,
only some of it was RAID1).  So yes, I "waste" cheap disc space in favour of
power consumption, case volume utilization, performance and resiliency. 
Building a 2TB RAID5 out of 5x500GB WD Blacks would cost £200 - only
slightly cheaper than a RAID1 of 2x2TB, and would draw about 2.5x the power.

I would also need to do a complete rebuild to upgrade to using 5x2TB,
whereas in a couple of years time, I expect I'll be able to buy a couple of
~10TB discs for about the same £228 (http://ns1758.ca/winch/winchest.html)
and install them in parallel whilst I migrate.  Once migrated, I'll run the
2TB discs until they die, storing stuff that matters even less than TV

Or I use unRAIDed filesystems or RAID0 for things that I really don't care


>> HOWEVER... many of the chipsets used on cheap SATA controllers are buggy:
>> <http://codemonkey.org.uk/2009/01/20/sata-disasters-silicon-image-3114/>
>> <http://marc.info/?t=123089876500001&r=1&w=2>
>> <https://bugs.launchpad.net/ubuntu/+source/linux/+bug/263160>
> Something plugged out of the blue obviously, and certainly a one-off
> occurrence.;

Those are seperate reports, and the SiL3114 and VT6421 are very popular on
the cheap SATA cards I find for readily available in the UK. Furthermore,
codemonkey.org.uk is Dave Jones' blog. Dave is one of the kernel devs, and
has worked for SuSE and Red Hat.

> JY

Best Regards,

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