[kwlug-disc] Encrypted disk vs Encrypted Home

[Ron Singh]

On Fri, Apr 24, 2020 at 2:32 AM Chris Irwin <chris at chrisirwin.ca> wrote:

> On Thu, Apr 23, 2020, at 19:15, Ron Singh wrote:
>
> I use laptops exclusively, I use Linux Mint all day long for my various
> jobs. I have a fleet of older Thinkpads I use for each biz/client.
>
> I grow more fearful of having my laptop du jour stolen.
>
> I have 3 identical laptops set up with Mint 18.2(based on Ubu 16.04 LTS)
> with the same power profile(using TLP).
> One has no encryption, 1 has encryption only on Home, the last has the
> entire SSD encrypted.
> - No encryption, idle temp is 39-40C (no issues on lap)
> - Encrypted Home,  idle temp is 42-45C (warm on lap but not uncomfortable)
> - Encrypted Disk, idle temp is 46-50C (uncomfortable as hell on lap)
>
>
> Does your workflow do a lot of Disk I/O? I can't imagine "normal" desktop
> use performs enough disk I/O to cause a 5-10 degree rise in temperature...
>
> As all the laptops are otherwise identical, have you tried swapping hard
> drives to confirm the only differing factor is disk encryption, and not
> something like the heatpipe being loose, failing fan, etc. (I've seen
> improved temperatures by reinstalling the heatpipes on my older thinkpads).
>
> FWIW, I'm on a Sky Lake t460 with full-disk luks, and my current CPU temp
> is also ~46°C, but I also have a consistent load average of >2 right now.
> Additionally, the dock blocks half the fan exhaust.
>
> However, the laptop still doesn't appear warm to the touch (granted, it's
> not on my lap), and I've never noticed it being particularly warm when on
> my lap unless I start putting unusual load on it, or block the fan intake
> with my clothes.
>
> I'll run wireless for a bit tomorrow and check temperatures to compare.
>
>
Nope on the disk I/O  -pedestrian use really, spreadsheets, text editor, FF
with a fair # of tabs(45-55). All of the TPs have been re-pasted recently
with Thermaltake kick-butt diamond-powder-infused(marketing 101!) paste,
all are running with Samsung 860 SSDs, so pretty sure they are as identical
as can be.

> Any ideas on how to get that Encryted Disk temps down? I have the CPU
> locked down at 1.2Ghz max(from 2.6Ghz), unused ports go to sleep, running
> an SSD, fan is set  for aggressive blowing to reduce internal chassis temp.
>
>
> I've reverted back to just standard Fedora config at this point. I see
> thermald is running, but I don't have TLP installed anymore.
>
> I do appear to be on the powersave governor, though I'm not sure why/how
> that was set. I'm somewhat surprised it wasn't ondemand...
>
> I believe there is a UEFI setting for system performance (on battery, on
> ac, etc), but couldn't tell you what mine is set to.
>
> Hubert has a great idea in trying various kernels, I start that process
tomorrow.

An FYI, before re-pasting, these X220/T520 devices with unencrypted SSDs
were idling @ 2%-4% CPU @ 39C-40C and the fan at around 2650-2992RPM. After
re-pasting with that mondo-uber-fab Thermaltake TG-8 paste, idling and
temps remained the same, but fan went down to 1992-2050RPM. The fan can
barely be heard on the unencrypted X220 and T520 with their fans around
2000RPM. Neat, eh?

Ron

-- 
> *Chris Irwin*
>
> email:   chris at chrisirwin.ca
>  xmpp:   chris at chrisirwin.ca
>   web: https://chrisirwin.ca
>
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