[EdLUG] Linux hibernate

[Andrew Smith]

Roy
I've probably fallen behind with updates, as my usual
apt-get upgrade
&
apt-get dist-upgrade
weren't doing anything, so resorted to
update-manager -d
It's still running after 4 hours, so hopefully I'll have a fully working
system when I  get up  Monday.
It actually completed in 5 hours, and successfully rebooted into kernel
5.15.0-47-generic
I have'nt tried hibernate  yet. I'll check  kernel release notes for any
references to hibernate, then maybe upgrade to a newer kernel, if relevant.
Andrew


On Sat, 17 Sept 2022 at 18:48, Roy <roy at crossford.net> wrote:

> Isn't the hibernate image compressed these days?
>
> That means that it might fit with some swap in use. It might not too.
>
> Regards,
>
> Roy Bamford
>
>
>
> On 17/09/2022 16:50, Geetam wrote:
>
> I only know the theory of hibernating, so please fill in a bit of
> hibernating knowledge that I do not have. (I am so old-fashioned that I
> shut down and boot up 😬 )
>
> When hibernating, the state of internal memory is stored on disk. Linux
> uses the swap partition on disk for this. So your swap partition needs to
> be large enough, i.e. at least as large as your internal memory - in your
> case 32Gb
>
> BUT WHAT HAPPENS when you have so much open on your desktop that your
> internal memory wasn't big enough and some of the less active processes
> have been swapped to swap space? (I am sure most of us avoid that, but that
> is what swap space is for, isn't it?)
>
> Say you have 40GB in use (32Gb in internal memory, 8Gb swapped to swap
> space). Is hibernating going to try to save 40GB into swap space? That
> won't fit into the 32Gb swap partition... Or is it only writing the 32Gb in
> internal memory to the swap partition clobbering the 8Gb that was there?
> Then the full state of your desktop cannot be restored.
>
> Is this maybe why Andrew is not able to hibernate?
>
> I am sure someone in the Linux world has thought about this, but I think
> we have forgotten because we try to have so much internal memory that swaps
> space is not used and the issue hardly ever arises these days. Still, I am
> curious 🤔
>
> Regards
> Geetam
>
> --
> I don't know
> ...
> I don't know what it is
> ...
> I don't know what it is that I don't know
>
> Isn't it beautiful
>
>
> On Fri, 16 Sept 2022 at 08:04, Colin Shorts <colin.shorts at gmail.com>
> wrote:
>
>> Hi Andrew, I'd be inclined to add a smidgen more swap to be on the safe
>> side.
>>
>> I take it `sudo pm-hibernate` doesn't work (correctly) either? Are the
>> kernel parameters getting set at boot (I think dmesg should say which
>> device will be used)? Is your swap partition on lvm, are you mounting it
>> using the uuid?
>>
>> I'm in the middle of redecorating my home office or I'd give it a bash
>> myself 😃
>>
>> Cheers,
>> Colin
>>
>> On Fri, 16 Sept 2022, 01:16 Andrew Smith, <asmith9983 at gmail.com> wrote:
>>
>>> Hi Colin
>>> I have 32Gb of swap, with *htop* reporting  none used in normal
>>> operation.
>>> Suspend works OK. Given the minimal energy consumed overnight on
>>> suspend, I may just continue using that until I can investigate further
>>> how  *suspend-then-hibernate* is meant to operate by reading the
>>> sourcecode of *systemctl. *
>>> Andrew
>>>
>>>
>>> On Wed, 14 Sept 2022 at 20:07, Colin Shorts <colin.shorts at gmail.com>
>>> wrote:
>>>
>>>> I'm no expert on hibernate (I use suspend myself), but iirc you'll need
>>>> at least as much free swap as system ram +used swap. 64GB doesn't sound
>>>> unreasonable as a starting point assuming you've got enough space and
>>>> considering how much Chrome can chew up.
>>>>
>>>> -Colin
>>>>
>>>> On Wed, 14 Sept 2022, 18:03 Andrew Smith, <asmith9983 at gmail.com> wrote:
>>>>
>>>>> Guys
>>>>> For quite a while, I've been putting my system into suspend mode,
>>>>> which was successful , apart from an odd occassion.  I now want to try
>>>>> saving more energy
>>>>> I've tried powering down, but would like it to restart in the same
>>>>> state rather than with a new login, as I had with suspend.
>>>>> I've tried "systemctl suspend-then-hibernate" from root CLI, but  I
>>>>> get essentially  a fresh boot.
>>>>>
>>>>> Any suggestions ?
>>>>> I'm running kernel 5.4.0-125-generic from Ubuntu, in 32Gb RAM, and
>>>>> typically have a around hundred tabs open on Chrome.
>>>>> Andrew
>>>>> --
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