[ale] odd device stuff

[Jim Kinney via Ale]

A recent system upgrade on a CentOS7 system puts it one revision ahead
of other machines. I've not found a notice in changelog that explains
what I see.

3 hard drives with 3 partitions on each. /dev/sd[abc] shows no
partitions (no /dev/sda1,2,or 3). If I run partprobe, magic happens and
they reappear. Then I can run blkid to get UUID for /etc/fstab
mounting. Mounts using UUID come from /dev/mapper/<long drive makers ID
string here with a partition number on end>.

reboot.

All the /dev/sda1,2,3 partitions vanish in /dev. The mounts work with
UUID. partprobe creates all the appropriate devices again.

Choose the older kernel (newest is kernel-3.10.0-693.21.1.el7.x86_64.
Older is kernel-3.10.0-693.5.2.el7.x86_64). Same scenario.

Other systems running older kernel only do not show this behavior.
Multipathd?

pvcreate wants a /dev/sdXN device which don't actually work. Ideas??

[Phil Turmel via Ale]

Post by Jim Kinney via Ale
All the /dev/sda1,2,3 partitions vanish in /dev. The mounts work with
UUID. partprobe creates all the appropriate devices again.
Choose the older kernel (newest is kernel-3.10.0-693.21.1.el7.x86_64.
Older is kernel-3.10.0-693.5.2.el7.x86_64). Same scenario.

Sounds like an udev rule changed, causing the initial device to be
created in /dev/disk/ or similar instead of /dev/.

Post by Jim Kinney via Ale
Other systems running older kernel only do not show this behavior.
Multipathd?

Hmm. Possible. If multipath picks up a device first, it won't get
processed the regular way. I've disabled multipath before for this
reason. (Blacklisted the module -- if you actually need it, you'll have
to dig into its conf files.)

Post by Jim Kinney via Ale
pvcreate wants a /dev/sdXN device which don't actually work. Ideas??

pvcreate should be happy with /dev/disk/* link and will generally then
work no matter where or what name that device gets in the future.

Phil
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[Jim Kinney via Ale]

I cheated and reinstalled. The box had already fallen dead once. I
spent an hour+ chasing ghosts and cut my losses.

As I grep'ed through the kernel changelog I don't recall udev changes.

Post by Phil Turmel via Ale

Post by Jim Kinney via Ale
All the /dev/sda1,2,3 partitions vanish in /dev. The mounts work with
UUID. partprobe creates all the appropriate devices again.
Choose the older kernel (newest is kernel-3.10.0-
693.21.1.el7.x86_64.
Older is kernel-3.10.0-693.5.2.el7.x86_64). Same scenario.

Sounds like an udev rule changed, causing the initial device to be
created in /dev/disk/ or similar instead of /dev/.

Post by Jim Kinney via Ale
Other systems running older kernel only do not show this behavior.
Multipathd?

Hmm. Possible. If multipath picks up a device first, it won't get
processed the regular way. I've disabled multipath before for this
reason. (Blacklisted the module -- if you actually need it, you'll have
to dig into its conf files.)

Post by Jim Kinney via Ale
pvcreate wants a /dev/sdXN device which don't actually work.
Ideas??

pvcreate should be happy with /dev/disk/* link and will generally then
work no matter where or what name that device gets in the future.
Phil
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Ale mailing list
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