Leslie Rhorer <lrhorer <at> satx.rr.com> writes:

	Any failed drives are moved to spare status.  Issue the `mdadm -D
/dev/mdX` command, and it will probably show 3 failed drives.

You are correct.

quoted

Why are three drives assumed to be spares?

	It's not assumed.  If was almost surely forced by md / mdadm.

Is there any way to get md or mdadm to tell me how it is making this decision? 
If I run "mdadm -Afv /dev/md0 /dev/sd[bcdef]1" I see this in messages:

Jun 11 07:22:10 fileserver kernel: md: md0 stopped.
Jun 11 07:22:10 fileserver kernel: md: unbind<sdd1>
Jun 11 07:22:10 fileserver kernel: md: export_rdev(sdd1)
Jun 11 07:22:10 fileserver kernel: md: unbind<sdb1>
Jun 11 07:22:10 fileserver kernel: md: export_rdev(sdb1)
Jun 11 07:22:10 fileserver kernel: md: unbind<sdc1>
Jun 11 07:22:10 fileserver kernel: md: export_rdev(sdc1)
Jun 11 07:22:10 fileserver kernel: md: unbind<sdf1>
Jun 11 07:22:10 fileserver kernel: md: export_rdev(sdf1)
Jun 11 07:22:10 fileserver kernel: md: unbind<sde1>
Jun 11 07:22:10 fileserver kernel: md: export_rdev(sde1)
Jun 11 07:22:27 fileserver kernel: md: md0 stopped.
Jun 11 07:22:27 fileserver kernel: md: bind<sde1>
Jun 11 07:22:27 fileserver kernel: md: bind<sdf1>
Jun 11 07:22:27 fileserver kernel: md: bind<sdc1>
Jun 11 07:22:27 fileserver kernel: md: bind<sdb1>
Jun 11 07:22:27 fileserver kernel: md: bind<sdd1>

All the ATA and SCSI messages in the log appear normal -- there are no warnings
or errors that I can see.

No doubt at least one of the drives probably has enough
info on hand to be able to recover most if not all of the information.  You
should be able to force assemble (-A -f) the array using at least 4 drives,
or perhaps all six.

I tried all combinations of three out of the five drives, but at most two
drives ever get used:

# mdadm -Af /dev/md0 /dev/sd[de]1
mdadm: /dev/md0 assembled from 2 drives - not enough to start the array.
# mdadm -Af /dev/md0 /dev/sd[bcd]1
mdadm: /dev/md0 assembled from 1 drive and 2 spares - not enough to start the \
array.
# mdadm -Af /dev/md0 /dev/sd[bce]1
mdadm: /dev/md0 assembled from 1 drive and 2 spares - not enough to start the \
array.
# mdadm -Af /dev/md0 /dev/sd[bcf]1
mdadm: No suitable drives found for /dev/md0
# mdadm -Af /dev/md0 /dev/sd[cde]1
mdadm: /dev/md0 assembled from 2 drives and 1 spare - not enough to start the \
array.
# mdadm -Af /dev/md0 /dev/sd[cdf]1
mdadm: /dev/md0 assembled from 1 drive and 2 spares - not enough to start the \
array.
# mdadm -Af /dev/md0 /dev/sd[def]1
mdadm: /dev/md0 assembled from 2 drives and 1 spare - not enough to start the \
array.


Thanks for the advice,
Dave