[Gllug] Large raid 5/5+0 setup

[Justin Perreault]

Hi everyone,

I've started searching the net to get a better understanding about raid
5/5+0 and the hit I can expect on performance.

I might be barking up the wrong tree and if so please point me in a more
useful direction.

The purpose of my searching is to sort out my myth-tv needs. I am
currently thinking that I would like to have 20 x 1TB SATA drives in a
raid 5+0 configuration for my backend server which would be responsible
for the recording of all of the shows/channels I currently track and
distribution to the front end machines where I would be able to watch
what was recorded. (I might consider 1.5TB drives but I am already
getting concerned about a system being able to handle it all)

There would be an average of about 3250 Kb/sec written to the storage
with peaks of 5800 Kb/sec.

I am guestimating that I will have 1 drive fail every 4-6 months with
the possibility that more than one will fail within a short period of
time. With this happening rebuilding the replacement drives I think I am
looking at 15-30+hours each. Hot swapping is currently part of the plan.

This is a non-critical system. Having said that I would likely be
accessing shows from it daily and I am considering some of the other
features that are available for use on MythTV.

Amount of space actually available seems odd, one stat I found suggested
that it might be as high as 86%. I suspect that the stat is correct and
that I am missing something about the effect of 5+0 raid on space usage.

I have started to wrap my head around the needs of the motherboards bus
and I am considering using expansion cards if that will help me get past
that bottle neck.

I still have not found a clear(for me) benchmark to determine the speed
of processor I will need. Nor am I sure how much of a hit I can expect
on performance while it is rebuilding.

I am willing to consider multiple system solutions. I believe that
multiple myth-tv back ends are able to play nice together. Hmm.. I'll
look into that a bit more.

If anyone has any thoughts/direction I would greatly appreciate the
feedback.

Justin

-- 
If you are an adult, you can choose to act like a child. If you do not
accept being an adult, you are only a child. -JJJ

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