Re: Power HA and Journaling.

Yes force ration of 1 would be bad.

Because journaling bundles writes is the biggest piece. You may have an interactive program that updates 50 or more rows across a dozen tables. If you did a force of 1 to every table that means 50 hard writes. If you journal then you get all 50 of those writes in one 'blob' through the journal into the receiver. Much like 1 truck with a pallet full of boxes vs 50 YuGos with one box each. Once they are in there DB management considers them 'Written' and from there assures they get to the appropriate tables. This happens asynchronously and after your program has already moved on.

This is a big part of why turning on journaling for a thousand tables might not even be noticeable performance wise and in some situations we have seen Improvements in performance!! Now if you were silly enough to journal every table to it's own journal, um, we're back to 'bad' :-)

Please ladies and gentlemen, do not fear the journal!!

- Larry "DrFranken" Bolhuis

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

On 1/29/2015 11:11 AM, Horn, Jim wrote:

We had this discussion with them in the past. We managed to get buy
without errors without journaling but -

I said - "why not a force ratio of 1 on the files"
they said - "too slow"
I said "why is it slower than journaling"
Received no response I could understand other than "trust us"
Anyone have an explanation I might be able to understand?

Jim

message: 5
date: Thu, 29 Jan 2015 15:43:00 +0000
from: Stefan Tageson <Stefan.Tageson@xxxxxxxx>
subject: RE: Power HA and Journaling.

Hi Rick,

Short answer: Due to the fact of Single Level Storage, many objects will
reside in memory. Journaling is the way of forcing them to disc where
PowerHA can replicate them.

Best regards

stefan.tageson@xxxxxxxx
M +46?732 369934