megaraid causing high-load
dlucas at comsltd.com
Wed Mar 9 08:08:01 CST 2005
> the first things i'd check are making sure you have the latest
> firmware on
> your controller. in my experience the load average normally rises
> when you
> find the system is queueing requests - i.e it can't read or write fast
> to keep up or the other side, it can't push the data out fast enough (the
> network interface for example is congested). you can sometimes catch
> this using iostat (though not very reliably :-/) and watching for a
> while at
> the avgrq-sz avgqu-sz await values.
I have been catching pend_cmds != 0 requests by watching
> The load never really drops low ... always hovering around the
> 0.10-0.40 mark even when the system is barely idle.
> heh. on our fileserver.
> 14:03:48 up 70 days, 4 min, 2 users, load average: 75.99, 85.89,
> 0.1-0.4 is busy ? you're kidding me right ? :-)
Considering it is doing next to NOTHING, I would expect a near 0 load. I
am just in the process of configuring it for an inhouse mail and other
file services and it is sluggish beyond reason!!! However, I must say 80
is good ;)
> i'm assuming 1G here..
I chatise people myself for this error and here I go making it ... yes,
of course 1G
> i wouldn't turn off swap myself.. but there may be some tuning that is
The system is barely loaded at the moment ... turning swap off was an
attempt to see if this was a potential problem area (which is was not)
> increase the memory to start with - i've found that increased
> buffering usually
> helps significantly with i/o queueing. i'd go to 2 or even 4G if you
> you haven't said too much else about what you're doing on the server..
> so it's
> hard to say much more about tuning it.. and unfortunately most of my
> stuff is all for 2.4 :-/
Basically the server is doing next to nothing ... inhouse fileserver and
mail for about 5 accounts. I would neverhave spec'd a machine so high,
but it was what they had!!! My prob is that it performs far worse than
even my PIII 450 at home serving more!!! The only reason I think it
performs at all is that is has 1Gb of mem, of which 75% is used as I/O
Still working on it ;)
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