[Bug 120375] Re: cannot boot raid1 with only one disk

ceg c.gatzemeier at tu-bs.de
Mon Aug 18 17:48:20 BST 2008

Dustin, you could have open a separate bug with your debconf patch to
track your work and at the same time keep the comunity updated and able
to give you feedback in a more organized manner.

> the default being BOOT_DEGRADED=false, which is the
conservative/traditional behavior.

Only some may consider this "conservative" behaviour a broken behavior,
when a system on a "redundant array of independent disks" will degrade
just fine when running, but won't even come up when booting.

The reason for all this restrictivity with starting arrays comes from
those start up scripts that use(ed) "mdadm --assemble --scan" to start
arrays. Those run whatever (partially) connected arrays they can get
hold of (in degraded mode).

IMHO the right thing for start up scripts to do is to only start arrays that are needed to set up the root device and fstab, and degrade only them after a timeout.
(/usr/share/initramfs-tools/hooks/cryptroot contains code to determine devices that the root device depends on.)

Hotplugging can start any arrays afterwards, if it is completely

The homehost "feature" is one suboptimal attempt to restrict array assembly. Same with the restriction with DEVICE or ARRAY definitions in mdadm.conf. Such restrictions add extra configuration burdens and should not be necessary with start up scripts that just correctly honor the root device and fstab information.

In fact the homehost, and ARRAY restrictions prevent the hotplugging
from beeing any better than manual configuration. Arrays still have to
be configured in mdadm.conf (Bug #252345) .

cannot boot raid1 with only one disk
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