Control: retitle -1 conflict between mdadm.shutdown and nutshutdown Control: reassign -1 nut-server 2.8.0-7
On Mon, 22 May 2023 12:24:15 -0700 Alex Meyer <debbug...@zezax.com> wrote: > Package: systemd > Version: 247.3-7+deb11u2 > > I'm running Debian bullseye with systemd. I also have installed mdadm > and nut-server. > > Looking in /lib/systemd/system-shutdown, I see two drop-in files with > contents as follows: > > mdadm.shutdown: > > #!/bin/sh > # We need to ensure all md arrays with external metadata > # (e.g. IMSM, DDF) are clean before completing the shutdown. > /sbin/mdadm --wait-clean --scan > > nutshutdown: > > #!/bin/sh > /sbin/upsmon -K >/dev/null 2>&1 && /sbin/upsdrvctl shutdown > > The man page for systemd-poweroff.service explains that: > > All executables in this directory are executed in parallel > > This is the problem. > > mdadm.shutdown is trying to delay the shutdown action until data > integrity can be guaranteed (for arrays with external metadata). > Meanwhile, nutshutdown will immediately turn off the power. These are > obviously incompatible. > > If execution were changed from parallel to sequential with a > deterministic ordering, this race condition could be avoided. > > There may also be other ways to address the problem, such as relocating > the mdadm stuff to some other spot in the systemd world. This is > speculation on my part, as I'm no expert on systemd. > > I should note that I do not personally have any md arrays with external > metadata. I do, however, have a UPS powering my Debian box and I can > verify that orderly shutdown causes it to de-energize immediately at > this point. I think it's self-evident that waiting for anything is > doomed to fail when run in parallel with powering off the host. > > So, to be clear, this is a design defect I noticed, not a problem I'm > experiencing. Still, it looks like a doozy, and I feel compelled to > report it. > > I see this as a structural problem. It's clearly documented as the > intended behavior. It doesn't depend on specific contents of my mdadm > or nut configuration files, nor on my specific kernel. Nevertheless: This is nothing to do with src:systemd, both of these are shipped by the respective packages, if they do not interact well then they need to be fixed there. Reassigning to nutserver as cutting power during shutdown seems the slightly worst of the two, but will let the two maintainers figure out if that's the right destination. -- Kind regards, Luca Boccassi
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