28 Feb
2025
28 Feb
'25
4:20 p.m.
On Fri, Feb 28, 2025 at 9:12 AM segaloco via TUHS <tuhs(a)tuhs.org> wrote:
On Friday, February 28th, 2025 at 8:04 AM, Dennis
Boone <drb(a)msu.edu>
wrote:
I've read several bits of guidance lately suggesting avoiding swap due to
the increasing prevalence of solid-state memories. The assertion is that
I/O heavy swapping, especially if you get into a thrashing state, is liable
to age current storage technologies much more than it would have in the
platter disk era. I've heard contrary opinions that it isn't as large of a
liability in reality. I haven't settled on one or the other, I keep a swap
file around on the microSD that runs my RPi, but I've only needed to
swapon, like OP, when compiling gcc.
Swapping to flash can be fine. The days when a "spot" could be worn out are
20 years in the past. If you use it as a "shock absorber" to cope with
transient loads, there's no issues.
However a lot depends on which kind of flash you have, you might have
trouble if the load is constant. Today there's a wide range of flash
drives. Ranging from < .1DWPD drives (you can't write even 10% of the
drive's capacity in one day w/o wearing it out in the warranty period) to
3, 5 or 10 DWPD drives. 0.3 and 1.0 seem popular in the consumer / prosumer
/ low-end-datacenter space. Those can be a problem if you are constantly
swapping (but again are fine for coping with transients).
The MicroSD is likely to be closer to the .1-.3 DWPD (unless you bought an
expensive one).
Warner
I’m
probably a lost soul on this issue, but swap space is just a way
to turn program bugs into performance problems.
You're hardly the only one. Some years ago, running Linux web and
database servers, I quit creating swap space. A runaway program would
turn the system into an infinite game of shuffle-the-pages well before
the OOM killer actually decided to kill something, and in that state,
one couldn't even reboot. This expanded the time window of "broken"
from tens of seconds, and perhaps a service restart, into tens of
minutes and a power button recovery. Every #$%^&* time.
De