I have an NVME drive as well as a spinning-rust drive. I've got swap on the spinning drive, but I'd like to put the hibernate area on the NVME. Is that possible, to have swap on one and hibernate on another?

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On 9/10/24 14:53, Stefan Monnier wrote:

I have an NVME drive as well as a spinning-rust drive. I've got swap on the >> spinning drive, but I'd like to put the hibernate area on the NVME. Is that >> possible, to have swap on one and hibernate on another?

Of course. Just tell your hibernation about the partition you want to
use for it (it usually defaults to using the swap partition).
IIRC the relevant file is `/etc/suspend.conf`.

Excellent, Where is documentation of the format I need? I can find examples
of pieces of it. That file doesn't exist by default.

You may also need to rebuild your `/boot/initrd.img` file since it
usually contains a copy of that information.

What is the command for that, "mkinitcpio"?

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On Tue, Sep 10, 2024 at 08:34:46PM -0400, eben@gmx.us wrote:

On 9/10/24 13:40, Charles Curley wrote:

On Tue, 10 Sep 2024 09:24:00 -0400
Eben King <eben@gmx.us> wrote:

I have an NVME drive as well as a spinning-rust drive. I've got swap
on the spinning drive, but I'd like to put the hibernate area on the NVME. Is that possible, to have swap on one and hibernate on another?

From what I understand, hibernation uses the swap area to store data,
so I expect the answer is "no".

However, why not move both the the NVME? You will speed up swapping considerably by doing so.

It probably would. I'm worried about shortening the life of the NVME drive with all those short writes. Do SSDs fail by going read-only, or do they just vanish and take your data with them?

Hm. That would depend on the failure mode and on the firmware. If the firmware itself fails, then all is gone. If what you're thinkig about is "write endurance",
these days it is measured in hudreds to thousands of TB [1] [2]. Yours has that number from the manufacturer, so you can look it up.

That said, it's swap (and hibernate), so hopefully the thing failing is just
an annoyance and not a significant data loss.

That (again) said, I've seen an installation (Ubuntu, I'm looking at you!) which refused to start just because the hibernation partition was indisposed, leading to an unnecessarily lengthy data recovery process, which is always traumatic for the owner.

Cheers

[1] https://www.tomshardware.com/reviews/intel-ssd-600p-nvme-endurance-testing,4826.html
(this one is 2017, but pretty detailed: expect things to have changed somewhat)
[2] https://www.anandtech.com/show/13761/the-samsung-970-evo-plus-ssd-review

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On Tue, 10 Sep 2024 09:24:00 -0400
Eben King <eben@gmx.us> wrote:

I have an NVME drive as well as a spinning-rust drive. I've got swap
on the spinning drive, but I'd like to put the hibernate area on the
NVME. Is that possible, to have swap on one and hibernate on another?

From what I understand, hibernation uses the swap area to store data,
so I expect the answer is "no".

However, why not move both the the NVME? You will speed up swapping considerably by doing so.

--
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https://charlescurley.com/blog/

--- SoupGate-Win32 v1.05
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I have an NVME drive as well as a spinning-rust drive. I've got swap on the spinning drive, but I'd like to put the hibernate area on the NVME. Is that possible, to have swap on one and hibernate on another?

Of course. Just tell your hibernation about the partition you want to
use for it (it usually defaults to using the swap partition).
IIRC the relevant file is `/etc/suspend.conf`.

You may also need to rebuild your `/boot/initrd.img` file since it
usually contains a copy of that information.


Stefan

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Hi,

On Tue, Sep 10, 2024 at 02:53:01PM -0400, Stefan Monnier wrote:

I have an NVME drive as well as a spinning-rust drive. I've got swap on the
spinning drive, but I'd like to put the hibernate area on the NVME. Is that
possible, to have swap on one and hibernate on another?

Of course. Just tell your hibernation about the partition you want to
use for it (it usually defaults to using the swap partition).
IIRC the relevant file is `/etc/suspend.conf`.

So, I think this just sets the resume= etc on the kernel command
line and I had thought that this only tells the kernel where to
resume *from*, not where to hibernate *to*. However I have not
tested that, and it seems that it might indeed also set where it
hibernates to as long as you first boot with that command line in
place:

https://wiki.archlinux.org/title/Power_management/Suspend_and_hibernate#Manually_specify_hibernate_location

Has anyone tried this?

Thanks,
Andy

--
https://bitfolk.com/ -- No-nonsense VPS hosting

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Hi,

On Tue, Sep 10, 2024 at 09:24:00AM -0400, Eben King wrote:

I have an NVME drive as well as a spinning-rust drive. I've got swap on the spinning drive, but I'd like to put the hibernate area on the NVME. Is that possible, to have swap on one and hibernate on another?

Kind of.

You can create multiple swap partitions or swap files, and you can
specify which one is used for resuming from hibernate:

https://wiki.debian.org/Hibernation/Hibernate_Without_Swap_Partition

So, you can create a swap partition or file on the NVMe and find out
its UUID, then put that UUID in the kernel command line for when it
resumes from hibernate.

I do not think, however, that you can influence where the kernel
hibernates *to* when it is running and is told to hibernate. I think
it might just use the first area that's big enough.

## Things to investigate

I'm not in front of a machine that uses hibernate right now.
Perhaps you could experiment with having a swap area on your HDD
that is too small for hibernate, and a big enough one on your
NVMe, with the correct kernel command line to resume from the
area on the NVMe? Point is, I am wondering if the kernel is
smart enough to pick a contiguous swap area that is big enough,
or if it will look at the first (or a random) area and bail out
when it sees it is not big enough.

There is also the concept of swap priority. If you look in "man
swapon" you'll see how to set that, and it can also go in fstab
like this:

# swap on your HDD
UUID=07d183ff-30a4-425b-9aa8-11d09adca34d none swap sw,pri=0
# swap on your NVMe
UUID=ead96714-efdf-4758-8124-a79aa98dd052 none swap sw,pri=10

The above would cause the swap area on your NVMe to be of higher
priority than the one on your HDD, so your kernel will choose to
swap to NVMe before HDD (undesirable for you). I do not know if
the hibernate procedure also chooses like that.

## Fiddly, but should definitely work

As a last resort, you could keep your NVMe swap area unused (not
have it in fstab) and override systemd's hibernate unit to do a
"swapon" for the NVMe area and a "swapoff" of the HDD area just
before it does the actual hibernate. Together with the kernel
command line settings, this will force hibernate to go to the
only swap area available at that time (NVMe) and then boot
resume from same.

Personally though all of this is a lot of hassle and I would
probably only put swap on the NVMe.

Thanks,
Andy

--
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On Tue 10 Sep 2024 at 19:14:54 (+0000), Andy Smith wrote:

Hi,

On Tue, Sep 10, 2024 at 02:53:01PM -0400, Stefan Monnier wrote:

I have an NVME drive as well as a spinning-rust drive. I've got swap on the
spinning drive, but I'd like to put the hibernate area on the NVME. Is that
possible, to have swap on one and hibernate on another?

Of course. Just tell your hibernation about the partition you want to
use for it (it usually defaults to using the swap partition).
IIRC the relevant file is `/etc/suspend.conf`.

So, I think this just sets the resume= etc on the kernel command
line and I had thought that this only tells the kernel where to
resume *from*, not where to hibernate *to*. However I have not
tested that, and it seems that it might indeed also set where it
hibernates to as long as you first boot with that command line in
place:

https://wiki.archlinux.org/title/Power_management/Suspend_and_hibernate#Manually_specify_hibernate_location

Has anyone tried this?

No, but https://www.kernel.org/doc/html/v5.10/admin-guide/kernel-parameters.html
says that "resume=
[SWSUSP]
Specify the partition device for software suspend
↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑
Format:
{/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>}"

Cheers,
David.

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On 9/10/24 13:40, Charles Curley wrote:

On Tue, 10 Sep 2024 09:24:00 -0400
Eben King <eben@gmx.us> wrote:

I have an NVME drive as well as a spinning-rust drive. I've got swap
on the spinning drive, but I'd like to put the hibernate area on the
NVME. Is that possible, to have swap on one and hibernate on another?

From what I understand, hibernation uses the swap area to store data,
so I expect the answer is "no".

However, why not move both the the NVME? You will speed up swapping considerably by doing so.

It probably would. I'm worried about shortening the life of the NVME drive with all those short writes. Do SSDs fail by going read-only, or do they
just vanish and take your data with them?

--
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to your boss' face, oh no. Eat a bucket of tuna-flavored pudding
and wash it down with a gallon of strawberry Quik. -- Weird Al

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On 9/11/24 01:04, Alexander V. Makartsev wrote:

On 11.09.2024 05:34, eben@gmx.us wrote:

It probably would.  I'm worried about shortening the life of the NVME drive >> with all those short writes.  Do SSDs fail by going read-only, or do they >> just vanish and take your data with them?

...

In mean time, I enjoy fast performance of SSD drives and keep an eye on them using "smartd".

Does smartd warn you about impending death?

--
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stops. The other says, "What's wrong?" "I've lost
an electron." "Are you sure?" "I'm positive!"

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On 10 Sep 2024 20:34 -0400, from eben@gmx.us:

I'm worried about shortening the life of the NVME drive
with all those short writes.

I would call that cargo cult by now. You presumably bought it to use
it, so use it. As already pointed out, typical write endurance for
modern SSDs is measured in tens to hundreds of terabytes written
(usually, for a particular model, it is a function of the drive size:
larger ones have a higher write endurance because there's more room to
spread writes around), and the firmware is likely sufficiently clever
to coalesce small writes in order to reduce write amplification. A
write endurance of just 100 TBW and a warranty period / expected
service life of five years translates to about _55 GB_ written per
day, every day, continuously for those five years. Look up the write
endurance specification for your particular model and consider whether
you are even close to the daily writes you'd need to be at to hit it.

You will definitely want backups of your data anyway for a myriad
_other_ reasons, so make sure you make regular backups; and of course
any piece of electronics can fail regardless; but write endurance
under intended usage of a SSD just isn't an issue in practice any
longer.

--
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On 11 Sep 2024 00:40 -0400, from eben@gmx.us:

You may also need to rebuild your `/boot/initrd.img` file since it
usually contains a copy of that information.

What is the command for that, "mkinitcpio"?

I believe that would be: sudo update-initramfs -u -k all

"-u" for update, "-k all" for all installed kernel versions.

See the man page for details.

--
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On Wed, 2024-09-11 at 08:43 +0000, Michael Kjörling wrote:

On 10 Sep 2024 20:34 -0400, from eben@gmx.us:

I'm worried about shortening the life of the NVME drive
with all those short writes.

I would call that cargo cult by now. You presumably bought it to use
it, so use it.

Absolutely. Having swap on a spinning disk is a terrible user experience, unless the machine simply isn't under much memory pressure and not swapping much anyway, so why worry about it. BTW, I highly recommend using zram as
the primary swap.

As already pointed out, typical write endurance for
modern SSDs is measured in tens to hundreds of terabytes written
(usually, for a particular model, it is a function of the drive size:

Instead of guessing, simply run "smartctl -A /dev/nvme0" to see the current numbers. Mine says 21% used after writing 36 TB during 33,418 power on
hours (3.8 years).

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