Re: CHGTCPA buffer sizes

AFAIK the only reason IBM kept the buffers low was to avoid wasting memory
on TCPIP connections. But now that we have more than enough RAM for stuff
like this bumping the buffers helps tremendously. I discovered this back on
power5 machines where moving the image catalogs would be a PITA, endless
hours to move the 20 or 30 cd images with the ftp doing 1 maybe 2 Mb/s ,
once i bumped it to 64k the 40mb controller couldn't catch up to the line
speed and you would see fluctuating speeds (also, beware of IO contention
and general system slowndowns when doing file transfers on machines without
enough IOPs)

Roberto

On Sat, Mar 5, 2016 at 12:20 PM, DrFranken <midrange@xxxxxxxxxxxx> wrote:

For "Many Moons" IBM i Defaulted to 8K for this. I believe it was i 6.1
that changed this to 64K but only on a new install, an upgrade did not
change it. So 64K is a good starting point. You may want to experiment with
even larger numbers, for example I use 1MB on the system I get PTFs from
IBM with. I also do parallel downloads and achieve from 4,500 to 5,000 MB
download speeds on each parallel download.


- Larry "DrFranken" Bolhuis

www.Frankeni.com
www.iDevCloud.com - Personal Development IBM i timeshare service.
www.iInTheCloud.com - Commercial IBM i Cloud Hosting.

On 3/5/2016 9:02 AM, Rob Berendt wrote:

Awhile back I complained about how long it took to ftp down 1-4GB image

catalog files from IBM straight to my IBM i.
It was suggested that I run CHGTCPA and change the buffer sizes.
I did and, OMG, what a difference that made!
I made the buffer size 65k. I think it was around 8k.
Instead of hours and hours the 4GB one was done in about 45-50 minutes.

I also broke them up into 7 separate downloads running at the same time in
batch.
So I'm still really not taxing the communications line.

I used to order them also on media and often the media beat the download.


Rob Berendt

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