CERC 1.5/6ch and high load averages, poor performance

[ross levins]

I have a similar box poweredge 1800 with cerc 1.5/6ch with six drives of 200 
GB each. This controller seems to be very slow. I have achieved upto 100 
MB/second sequntial read or write but I think that it should give 
100MB/second per port i.e. 100MB * 6 i.e. 600 MB/second.
Also when you are doing hardware RAID, what is the reason of using LVL?
As far as performance and load avergae during mysql load is concerned, I 
think that it depends on various factors i.e. what type of load is going 
on?How many concurrent users are doing loads/query? So I think that you will 
need to find more about mysql application is doing and get some performance 
data from mysql. Also I think it would be good to analyze vmstat and iostat 
data at OS level.
Thanks


>From: "Neil Jones" <ncjonez at gmail.com>
>Reply-To: ncjones at cs.ucsd.edu
>To: linux-poweredge at dell.com
>Subject: Re: CERC 1.5/6ch and high load averages, poor performance
>Date: Mon, 10 Jul 2006 19:26:00 -0700
>
>The CERC is supposed to be a rebranded Adaptec 6 channel SATA card (I
>don't remember the model number...maybe it starts with 2 and ends in
>0).  It uses the aacraid driver.
>
>It's currently got 4 drives (500 Gb), all the same model, in a RAID-5
>array.  That array is then managed by LVM under Linux (RHEL 4), and
>split into a couple of partitions.  The hardware itself is only about
>2 weeks old, and the drives haven't shown any problems when I verify
>them in the BIOS (and the raid status appears to be normal when I look
>at the disks in AFACLI).
>
>Prior to doing a MySQL load (say), the write performance is 50 Mb/s.
>During a MySQL load, the write performance is 2 Mb/s, and the loadavg
>shoots to 13.
>
>(Apologies, David, if you get a duplicate message.)
>
>..Neil
>
>On 7/10/06, David Hubbard <dhubbard at dino.hostasaurus.com> wrote:
> > I've seen that type of issue on crap 3ware controllers,
> > not sure who makes Dell's cerc for sata.  What kind
> > of raid have you configured?
> >
> > David
> >
> > > -----Original Message-----
> > > From: linux-poweredge-bounces at dell.com
> > > [mailto:linux-poweredge-bounces at dell.com] On Behalf Of Neil Jones
> > > Sent: Monday, July 10, 2006 7:28 PM
> > > To: linux-poweredge at dell.com
> > > Subject: CERC 1.5/6ch and high load averages, poor performance
> > >
> > > I have a (new) PowerEdge 1800 with a CERC 1.5/6ch controller.  It has
> > > a single 4 volume RAID 5 array, which is also controlled through Linux
> > > LVM; the system runs Red Hat Enterprise 4.
> > >
> > > I've noticed that when any application begins to do a lot of disk I/O
> > > (e.g., MySQL), the load on the machine jumps up to a very high number
> > > (currently, 13).  The applications themselves use very little memory
> > > and there is no swapping going on --- all disk I/O is coming from
> > > explicit file I/O from an application. The only processes that seem
> > > active are the I/O-heavy application, kjournald, and (oddly) kswapd.
> > >
> > > Has anybody seen this problem before, and if so, what did you
> > > do about it?
> > > --
> > > ..Neil
> > >
> > > _______________________________________________
> > > Linux-PowerEdge mailing list
> > > Linux-PowerEdge at dell.com
> > > http://lists.us.dell.com/mailman/listinfo/linux-poweredge
> > > Please read the FAQ at http://lists.us.dell.com/faq
> > >
> > >
> >
> > _______________________________________________
> > Linux-PowerEdge mailing list
> > Linux-PowerEdge at dell.com
> > http://lists.us.dell.com/mailman/listinfo/linux-poweredge
> > Please read the FAQ at http://lists.us.dell.com/faq
> >
>
>
>--
>..Neil
>
>
>--
>..Neil
>
>_______________________________________________
>Linux-PowerEdge mailing list
>Linux-PowerEdge at dell.com
>http://lists.us.dell.com/mailman/listinfo/linux-poweredge
>Please read the FAQ at http://lists.us.dell.com/faq

_________________________________________________________________
Don’t just search. Find. Check out the new MSN Search! 
http://search.msn.click-url.com/go/onm00200636ave/direct/01/