I have an AMD64 Gentoo (running systemd) build with a RAID0 root and some other arrays (RAID1 boot, RAID1 home etc..). The boot process is being slowed down quite dramatically as mdadm searches the arrays at boot (from the initramfs).

I've tried:

mdadm --detail --scan >> /etc/mdadm.conf

Removing info about metadata etc.. (as suggested elsewhere), and then telling Gentoo's genkernel to pull in the mdadm.conf into the initramfs through genkernel.conf.

But it's still holding up the boot process. I have an alternate distro (Debian) installed on a separate partition which also runs systemd and which boots much quicker. Any ideas?

  • My idea would be to read the initramfs scripts generated by the two systems, and see the differences in there. – Laszlo Valko Oct 10 '14 at 1:08

What's inside the mdadm.conf used by Debian vs Gentoo?.

Specifically, what is used for the DEVICE line. If that points to some slow device or is omitted, then mdadm will take a long time to probe.

Eg, on my system, I have a couple of /dev/sdX devices that correspond to SD card readers built into my monitors. They are present regardless of any SD cards being inserted, and probing them takes a non-zero amount of time.

You should narrow it down if possible.

The mdadm version may also be worth checking.

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