Systemd odpojuje disk pod rukama

[Jan Kasprzak]

	Dobry den,

mam takovy problem, ve kterem figuruje systemd (zadne prekvapeni :-).
Uz jsem to videl vickrat na ruznych strojich a zatim presne nevim ani
jak to obejit (jinak nez rebootem, coz bych nerad rutinne delal :-),
natoz jak tomu predejit.

	Servery s CentOS 7, mimo jine na nich bezi CEPH. Jako CEPH OSD
jsou montovane oblasti fyzickych disku (zadny RAID, SW ani HW), ve fstabu
pomoci UUID, treba takto:

UUID=ab45687c-ee65-4bcd-8269-ded16951ae9f /ceph2                  xfs     defaults        0 0

A ted je problem, ze pokud vypadne disk, ja disk vymenim nebo i jen pustim
badblocks a vratim ten stejny, tak ten disk nejde namontovat:

# mount /ceph2
# mount | grep /ceph2
# 

Mount projde, aniz by nahlasil chybu, ale disk namontovany neni.
Pak jsem zjistil, ze ten disk nekdo odpojuje - v dmesg je toto:

[316996.416465] XFS (sdc3): Mounting V4 Filesystem
[316996.466679] XFS (sdc3): Ending clean mount
[316996.471096] SELinux: initialized (dev sdc3, type xfs), uses xattr
[316996.484923] XFS (sdc3): Unmounting Filesystem

Zda se, ze systemd si dela z radku ve fstabu vlastni unit "ceph2.mount",
ktery pak sam odpoji:

# journalctl -u ceph2.mount
Oct 03 09:55:53 cephhost.fi.muni.cz systemd[1]: Unit ceph2.mount is bound to inactive unit dev-disk-by\x2duuid-ab45687c\x2dee65\x2d4bcd\x2d8269\x2dded1
Oct 03 09:55:53 cephhost.fi.muni.cz systemd[1]: Unmounting /ceph2...
-- Subject: Unit ceph2.mount has begun shutting down
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit ceph2.mount has begun shutting down.
Oct 03 09:55:53 cephhost.fi.muni.cz systemd[1]: Unmounted /ceph2.
-- Subject: Unit ceph2.mount has finished shutting down
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit ceph2.mount has finished shutting down.

Pritom ale /dev/disk/by-uuid/ab45687c-ee65-4bcd-8269-ded16951ae9f
existuje, jen po vytazeni a vraceni disku neukazuje na sdb3, ale sdc3:

# ls -l /dev/disk/by-uuid/
total 0
lrwxrwxrwx. 1 root root 10 Oct  3 09:41 ab45687c-ee65-4bcd-8269-ded16951ae9f -> ../../sdc3
[...]

Pokud napisu

# mount /dev/disk/by-uuid/ab45687c-ee65-4bcd-8269-ded16951ae9f /mnt1

tak se namontuje a zustane namontovany. Problem dela jenom, pokud
chci namontovat jako /ceph2.

Jak se da systemd vysvetlit, at dela to co pisu a nesaha mi pod ruky?
Diky,

-Y.

-- 
| Jan "Yenya" Kasprzak <kas at {fi.muni.cz - work | yenya.net - private}> |
| http://www.fi.muni.cz/~kas/                         GPG: 4096R/A45477D5 |
     "i wonder how it would be if joerg schilling wrote perl modules."
                                         -- from perldoc common::sense