From: Yard, John (jyard@AIS.UCLA.EDU)
Date: Thu May 13 2004 - 16:05:47 EDT
It ran a test using a procedure similar to that below.
I created two raid5 arrays, one with 4 physical disks,
one array with three. This appeared as 2 hdisks on the system.
I created a logical volume across these two hdisks.
the PP size for the volume group was 32meg. I ran
tests , first using cplv to copy data to the new
logical volume ( write data ), then running
dd if=/dev/lvname of=/dev/null for read data.
I get ~ 20M/sec read or write. My 2104s get the same or better.
I also tried creating a striped lv over the raid arrays,
as above, with little change. The fastt600 is 2G fiber attached
, so I think I should be getting much better performance.
I think if I create my raid arrays 4 disks each my results will
be better, but not by much.
Any suggestions very much appreciated,
John Yard
UCLA
jyard@ais.ucla.edu
-----Original Message-----
From: IBM AIX Discussion List [mailto:aix-l@Princeton.EDU] On Behalf Of
John Jolet
Sent: Thursday, May 13, 2004 10:11 AM
To: aix-l@Princeton.EDU
Subject: Re: Fastt600 Performance
We found significant speed differences depending on how we had the lvs
arranged on the 500/700. We're using it for oracle, so we set up 4
arrays, two on each controller and balance the raw lv creation between
the two controllers. We can get over 150 mb/sec on the 500, twice that
(of course) on the 700 (has a 2 gig backplane). How are your arrays
configured on the 600? You could fake load balancing by creating one
logical disk on each controller, adding both resulting hdisks to a vg
and creating lvs "striped" across the two hdisks....
Yard, John wrote:
> Software support recommended against load balancing,
>
> saying it would cause 'thrashing' of LUNs from one controller to
another.
>
> We are upgrading to 5.1 - not 5.2 for app reasons - in the near
future.
>
> Will there be some resolution on 5.1 ?
>
> Currently we are getting much better performance out of 10K rpm
>
> 2104s than on the 15K rpm fastt600, even though the fastt600
>
> was significantly more expensive,
>
> Jyard
>
> UCLA
>
>
------------------------------------------------------------------------
>
> *From:* IBM AIX Discussion List [mailto:aix-l@Princeton.EDU] *On
> Behalf Of *jeff barratt-mccartney
> *Sent:* Wednesday, May 12, 2004 5:08 PM
> *To:* aix-l@Princeton.EDU
> *Subject:* Re: Fastt600 Performance
>
> did you try chdev -l dar0 -a loadbalancing=yes
>
> -----Original Message-----
> *From:* IBM AIX Discussion List [mailto:aix-l@Princeton.EDU]*On
> Behalf Of *Yard, John
> *Sent:* Wednesday, May 12, 2004 4:30 PM
> *To:* aix-l@Princeton.EDU
> *Subject:* Fastt600 Performance
>
>
------------------------------------------------------------------------
>
> I have a new fastt600 direct attached to 2 h80's
>
> ( aix 4.3.3.). The fast Best Practices Guide
>
> talks about balancing LUNs across controllers,
>
> but when I did this with a raid device, creating
>
> a logical volume across 2 raid devices, tests
>
> showed the system reading not from both raid devices
>
> at the same time, but in round robin fashion.
>
> Thruput was not terrible, but was not exceptional
>
> either.
>
> Anyone have any experience or suggestions
>
> tuning the fastt600, or other fast devices ?
>
> Thanks,
>
> John Yard
>
> UCLA
>
> John Yard
>
> UCLA Administrative Information Systems
>
> Distributed Platforms
>
> Unix/Win2000 Admin/Sybase/Oracle/SqlSrvr/Networking
>
> 310-825-1725
>
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