Marcy,
Yes, that helps.
So let's say a virtual machine has 2G of initial, 8G of STANDBY, so thus
the max would have to be at least 10G. Then a user says 'I need 2G more'.
So you'd go to 4G initial, stay at 8G STANDBY for a new 12G max?
Thanks.
-Mike
On Mon, Aug 29, 2016 at 12:38 PM, Marcy Cortes <
[email protected]> wrote:
> So here we pretty much just leave standby alone at 8G.
> We wouldn't take any standby away if we increased the memory. We still
> want to have some there to be able to add in an emergency situation (and we
> have had to do that when apps had a memory leak but couldn't take a
> recycle).
>
> Does that answer what you are looking for?
>
>
> -----Original Message-----
> From: Linux on 390 Port [mailto:[email protected]] On Behalf Of
> Michael MacIsaac
> Sent: Sunday, August 28, 2016 7:50 AM
> To: [email protected]
> Subject: [LINUX-390] Linux and VM memory operations and The Principle of
> Least Astonishment
>
> Wikipedia says the “Principle of least astonishment” is that systems
> (software) should behave in a manner consistent with how users of that
> component are likely to expect it to behave, i.e., users should not be
> astonished at the way it behaves.
>
> I’m trying to apply this principle to memory operations on z/VM and Linux
> in zoom line commands.
>
> I believe Linux running on z/VM has 3 types of memory, all of which can be
> different:
> 1) That defined in the user directory
> 2) That defined in CP for a running system
> 3) That defined in and used by a running Linux
>
> While they can all be different, it's probably best to keep all three in
> sync so you can say "That Linux system has <amount> of memory."
>
> Then to complicate matters, there are maximum and 'standby' amounts, the
> latter of which is necessary if memory is to be added dynamically to
> running Linux systems. The initial, maximum and standby can also get out of
> sync in the user directory and again it's probably best that they don't
>
> First some terminology.
> -) 'soft reboot' - Linux 'init 6' - does not log off/on virtual machine
> -) 'hard reboot' - Linux halt, logoff, logon, boot
>
> So, for some hopefully intuitively named line commands, is this how you'd
> expect them to behave?
>
> zaddmemory linux1,linux2 1g
> Add 1g to user directory initial, CP and Linux memory on nodes linux1
> and linux2.
> If 'COMMAND DEF STOR <init> STANDBY <stby>' is found, add to <init>,
> subtract from <stby>
>
> zrmmemory linux1,linux2 1g
> Remove 1g from user directory initial, CP and Linux memory on nodes
> linux1 and linux2.
> If 'COMMAND DEF STOR <init> STANDBY <stby>' is found, subtract from
> <init>, add to <stby>
>
> zaddmemory --initial linux1 1g
> Add 1g to user directory initial only => take effect after hard reboot.
> If 'COMMAND DEF STOR <init> STANDBY <stby>' is found, add to <init>,
> subtract from <stby>
>
> zaddmemory --temp linux1 1g
> Add 1g to running linux1 only => will be gone after hard or soft reboot,
> no change to user directory.
>
> zsetmemory --maximum linux1 8g
> Set linux1 maximum meomory to 8G in user directory.
> If 'COMMAND DEF STOR <init> STANDBY <stby>' is found, set <stby> to <max>
> - <init>.
>
> zsetmemory --standby linux1 7G
> Set linux1 standby memory only to 7G.
>
> Let me add some feedback as I think about the last example - setting
> STANDBY only would by definition get settings out of sync, so maybe it
> would be astonishing to allow such an option.
>
> Thanks for any feedback.
>
> -Mike MacIsaac
>
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