RE: Hosting Linux partitions on IBM i

Patrik,

Gott segnen sie!

My apologies for being rather slow at replying. I've started to reply several times and another interruption happens. I really appreciate your response. I'll reply in-line below

Danke,
Michael Quigley
Computer Services
The Way international
www.TheWay.org

-----Original Message-----
From: MIDRANGE-L <midrange-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf
Of Patrik Schindler
Sent: Tuesday, September 29, 2020 11:09 AM
To: Midrange Systems Technical Discussion <midrange-
l@xxxxxxxxxxxxxxxxxx>
Subject: Re: Hosting Linux partitions on IBM i

Here it is one more detailed:

https://try-as400.pocnet.net/wiki/File:IVirtualization_-
_IBM_iHost_and_Client_LPAR_Easy_Install_Guide_v5.03_TR7.pdf

I could not find that PDF online anymore, so I put it on my server.

[Michael Quigley]
Excellent link! I've started reading through it. I know IBM added functionality since this was published, but it seems to still be relevant.

What all of the docs omit is: How to actually boot and kickstart the install?
Well, put the iso image into an image catalog on the hosting i LPAR, mount
it and the LPAR firmware will happily boot it.

Also, for watching the boot process, and setting initial configuration, you'll
need a console, and this is *not* an 5250 console, but a VT100 one.

I'm thinking I have to release some of the memory from our IBM I partition

before I can allocate any to the Linux partitions.

Of course. And CPU. This is possible at run-time. With a HMC at least.

[Michael Quigley]

We do not have an HMC. :-(

Also, I'm not sure how much memory would be required to run a simple

Linux partition.

If you omit the graphical environment completely (we're talking about a
server, yes?), then you'll be fine with as little as 512 MB. Yes, Megabytes.
This is completely sufficient for a Linux "doing nothing" besides having the
basic services running like ssh, ntp, cron/at, postfix (for delivering output
generated by cron/at), and syslog.

There are ways to see if Linux needs more RAM. The most important is to
watch the output of vmstat 2 while the machine is busy. Watch the si and so
columns. If they constantly show activity in the low 2-digit range, you maybe
need to add RAM, soon. (End vmstat with Ctrl-C) If the numbers are three or
even four digits, add RAM *now*. :-) How much? "depends". I start with
doubling the amount, so I'm safe.
The output of "free" or "top" regarding the total amount of used swap space
is *not* an indication of lack of RAM! Over hours and days, the kernel puts
rarely used pages of allocated memory on disk, to free memory for more
buffers.

[Michael Quigley]
Great advice. I'll start with a minimal set up and increase as needed. As I said, we're not planning on anything very heavy. But we figure we've got the big POWER9 box and we would like to take advantage of some of the horsepower.

(As indicated above, our goal is not a high-capacity server. Just
something for primarily our small IT department.)

I'd recommend to give it a go with 1 GB and a disk file with 8 GB for a
minimum install. You can add more disk files later and depending on the
install, either use LVM to add that new virtual disk to the volume-group, and
in turn enabling you to resize the logical volume(s) where the filesystems
reside. This is possible at run-time also. If there's no LVM, you need to
prepare the new disk for a part of the directory tree needing space, copy that
over, prepare /etc/fstab to mount that volume at boot time, and delete the
old tree. Known candidates are /var or /home. More details on request.

Any advice or a pointer to a detailed explanation of the requirements

would be much appreciated.

Please provide more detailed explanation what exactly you'll run on the
LPARs. :-) Even if I've 25 intense years of Linux experience, my crystal ball is
still broken. ;-)

[Michael Quigley]
I haven't been able to repair my crystal ball either.

We will host one couple of webpages developed in C#. These help us track tasks, projects, as well as some data on PCs. The data is all stored in Db2 for I tables. We've been running it on a sandbox Windows server, but we need to set up development and production environments. We would like these two environments to look the same and I don't think we have that many Windows Server licenses to play with. (That and I would like to utilize more of the capability of the POWER9 box.)

:wq! PoC

PGP-Key: DDD3 4ABF 6413 38DE - https://www.pocnet.net/poc-key.asc


--
This is the Midrange Systems Technical Discussion (MIDRANGE-L) mailing
list To post a message email: MIDRANGE-L@xxxxxxxxxxxxxxxxxx To
subscribe, unsubscribe, or change list options,
visit: https://lists.midrange.com/mailman/listinfo/midrange-l
or email: MIDRANGE-L-request@xxxxxxxxxxxxxxxxxx
Before posting, please take a moment to review the archives at
https://archive.midrange.com/midrange-l.

Please contact support@xxxxxxxxxxxxxxxxxxxx for any subscription related
questions.

Help support midrange.com by shopping at amazon.com with our affiliate
link: https://amazon.midrange.com