[mythtv-users] Software RAID5 no improvement to transferspeed...

Johnathon Meichtry johnathon-dev at meichtry.org
Thu Jan 12 16:47:31 UTC 2006


Hi Steve,

Cool!

On my modern 3.6GHZ server, cpu usage on raid is negligible - something less 
than 1% but on much slower machines in the past I have seen it up around 3% 
so the point I was trying to make was that it should never cause the CPU to 
head up into the 90's under even the most extreme situation unless of course 
there is some major a bug.

My IO waits are a different matter.  If software RAID (RAID1) is in use and 
server is busy, io waits (wa) never really exceed 10% but with my hardware 
RAID5 array frequently I see it getting up to 40% io waits if it is really 
busy.  Its quite ironic as that is why I paid loads of money for it - my bet 
is there is a bug in the controller firmware but the manufacturer doesn't 
seem to be doing much about it at least the server performs well so I don't 
bother myself too much over it.

If your load averages are 0.40 then to me that is fine but if it is 4.00 
then that is not so good as most Unix pros would consider that to be an 
overloaded CPU.  Of course its all speculation and people interpret load 
averages differently.

Regards,

Johnathon

----- Original Message ----- 
From: "Steve Adeff" <adeffs at gmail.com>
To: <mythtv-users at mythtv.org>
Sent: Thursday, January 12, 2006 4:21 PM
Subject: Re: [mythtv-users] Software RAID5 no improvement to 
transferspeed...

Just to let you guys know, it was an SQL issue, I sent a new email, but
changed the subject announcing it... I had my other machine (over 100bT)
running the SQL db, once I moved it back to the local machine it plays back
fine.

thanks for the info though, some good info.

Johnathon: I don't even notice 3% use by the RAID, I've seen %wa as high as
6%. I get load averges around 4 while watching HD and recording 2 shows.

Ramses: great command! I need to store that to my repertoire.

-- 
Steve
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