Recently, I started using overlay filesystem. I'm using initram script (init=/sbin/myint) as described in Raspberry blog - raspberry overlay, yet, I noticed that it increases boot time significantly (about 10 seconds).

Is this increase in time happening because of mounting overlay filesystem?


I see that if I do the mount in init script instead of fstab file, then the additional time is reduced. Yet, I am not sure what's the difference. in fstab:

/dev/mmcblock5      /app    ext4       defaults 0 0
overlay             /app    overlay defaults,lowerdir=/app,upperdir=/mnt/temp/upper2,workdir=/mnt/temp/work2

(/temp is mounted in initram script (init=/sbin/myint), see the link above) in /etc/local.d/01.start :

mount -t overlay -o lowerdir=/app,upperdir=/mnt/temp/upper2,workdir=/mnt/temp/work2 none /app
  • Are you loading overlay or overlay2? - unix.stackexchange.com/questions/328978/docker-and-overlayfs. – slm Aug 19 '18 at 18:22
  • I use overlay, not overlay2. – ransh Aug 19 '18 at 18:25
  • Try w/ overlay2 to see if that's the issue. – slm Aug 19 '18 at 18:25
  • 1
    you could try comparing the output of systemd-analyze blame and/or systemd-analyze plot > plot.svg. It might show which parts of the boot process happen more slowly / later on. – sourcejedi Aug 19 '18 at 19:51
  • I made some progress , I see that if I mount the overlay in init script instead of fstab, the additional time is reduced. quite strange. any idea what's the difference ? The question was edited – ransh Aug 20 '18 at 7:52

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