From: Yard, John (jyard@AIS.UCLA.EDU)
Date: Thu May 13 2004 - 18:17:07 EDT
There is a difference; I have been testing with bs=4096
and it is significantly slower with bs=1024 :
[urrept:/usr/local/bin] # timex dd if=/dev/worktest5 of=/dev/null
bs=4096
1253376+0 records in.
1253376+0 records out.
real 248.09
user 5.29
sys 103.49
You have mail in /usr/spool/mail/root
[urrept:/usr/local/bin] # timex dd if=/dev/worktest5 of=/dev/null
bs=1024
5013504+0 records in.
5013504+0 records out.
real 393.49
user 20.24
sys 219.45
JYard
UCLA
-----Original Message-----
From: IBM AIX Discussion List [mailto:aix-l@Princeton.EDU] On Behalf Of
John Jolet
Sent: Thursday, May 13, 2004 1:31 PM
To: aix-l@Princeton.EDU
Subject: Re: Fastt600 Performance
one other thing....if you add bs=1024k to your dd command, does
performance change?
Yard, John wrote:
>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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