Can a loop thrash a disk?

lucmove · 05-05-2023, 01:10 PM

Code:

#!/bin/sh

for i in `seq 1 10`
    do echo $i >> loop.txt
done

Does that code write to the loop.txt file 10 times? How about `seq 1 10000000`? Does that write to disk 10 million times?

I am specifically concerned with wearing out my SSD.

pan64 · 05-05-2023, 02:02 PM

you need to read about disk cache. for example: https://foxutech.com/linux-memory-and-disk-caching/

michaelk · 05-05-2023, 02:28 PM

Look at the specifications of the SSD and post what the value of its TBW or DWPD. DWPD is the amount of drive capacity you can write per day over the warranty period. TBW is the total number of writes for the life of the drive and from there you can determine the writes per day. In most cases that far exceeds what most home users normally write to disk.

MadeInGermany · 05-05-2023, 04:28 PM

In most cases there is enough free RAM, so buffering and few bundled disk writes take place.
But if you want to be safe then optimize your code

Code:

for i in `seq 1 10`
    do echo $i
done > loop.txt

dugan · 05-05-2023, 05:08 PM

Put loop.txt on tmpfs when it's being written to, and move it to the SSD after that's all done?