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Thee be having a math problem in here somewhere.!.

First off those ARE real disk arms and you have 20 of 'em.

Those disk arms have a 3GB interface and one single arm could handle about 1Gb sustained write performance. So in theory one single drive could accept all 32GB in about 4.3 minutes or all 20 drives writing flat out could handle it in under 15 seconds, IN THEORY!

Of course it doesn't work ANYTHING Like that in reality with RAID reads and updates it's twice that at minimum and even then that's in a perfect world.

We can do theory math all day but what I would do is wait until a time when you can shut the system down. Then do a PWRDWNSYS *IMMED and time it. Of course you'll not have any users on then and not have any significant number of files open etc so this will be a 'Best Case' power down time. Figure double that and you're likely safe.


- Larry "DrFranken" Bolhuis

www.frankeni.com
www.iDevCloud.com
www.iInTheCloud.com

On 6/13/2013 4:24 PM, Buck Calabro wrote:

It's often said that there's no stupid question, but I think I'm about
to test this adage. I've got my cable set between the UPS and the 720
(8202-E4C). I got the CPI0962 (UPS now attached) message. I don't have
a UPS power handling program written yet, so I want to set QUPSDLYTIM to
a value that will allow the machine to write main store to disk before
crashing. I look at
http://pic.dhe.ibm.com/infocenter/iseries/v7r1m0/index.jsp?topic=%2Frzahr%2Frzahrdlytimco.htm
(Determining the value of QUPSDLYTIM) and I can see that the value is
heavily dependent on the number of disk arms and main storage.
WRKSYSSTS and a calculator tell me I have the 32GB we paid for :-)
WRKDSKSTS tells me I have 8 198C disk units and 12 19B0 disk units. If
that's 20 arms, I'm hosed - the table says it'll take (worst case) 58
minutes to write 32GB RAM to disk (!) [1]

And so, I don't think those 20 disk units equal 20 disk arms but my
Google-fu has failed me in finding a conversion table. I tried Power
720, 8202-E4C, 198C, 19B0. Is 'disk arm' an imaginary unit of measure
like CPW?
--buck

[1] These numbers seem crazy even if worst case. It's really going to
take an hour to write 32GB of data from RAM to disk?


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