[linux-lvm] problem with lvcreate and redirection of stdout/stderr

Lentes, Bernd bernd.lentes at helmholtz-muenchen.de
Wed Aug 20 15:27:52 UTC 2014

Hi ML,

i'm writing a script to update my servers. Before updating, i'd like to create a snapshot of the root-directory (/). If something goes wrong with the update, I have a consistent backup.
I try to redirect stdout and stderr to a logfile for being able to check everything afterwards. The redirection has problems with lvcreate.
This is my script (excerpt):

lvremove -fv /dev/vg1/lv_root_snapshot &> /var/log/update.log

lvcreate -v -L 45G -n lv_root_snapshot -s vg1/lv_root >> /var/log/update.log 2>&1

zypper -n up -y -t patch  --skip-interactive >> /var/log/update.log 2>&1

With the second line I try to create the lv and redirect stdout/stderr to a log file.
The whole system stop by executing the second line, this are the last lines in my log:

lvcreate    Setting logging type to disk
lvcreate    Setting chunksize to 8 sectors.
lvcreate    Finding volume group "vg1"
lvcreate    Archiving volume group "vg1" metadata (seqno 99).
lvcreate    Creating logical volume lv_root_snapshot
lvcreate    Creating volume group backup "/etc/lvm/backup/vg1" (seqno 100).
lvcreate    Found volume group "vg1"
lvcreate    activation/volume_list configuration setting not defined: Checking only host tags for vg1/lv_root_snapshot
lvcreate    Creating vg1-lv_root_snapshot
lvcreate    Loading vg1-lv_root_snapshot table (252:1)
lvcreate    Resuming vg1-lv_root_snapshot (252:1)
lvcreate    Clearing start of logical volume "lv_root_snapshot"
lvcreate    Creating logical volume snapshot0
lvcreate    Found volume group "vg1"
lvcreate    Found volume group "vg1"
lvcreate    Creating vg1-lv_root-real
lvcreate    Loading vg1-lv_root-real table (252:2)
lvcreate    Loading vg1-lv_root table (252:0)
lvcreate    Creating vg1-lv_root_snapshot-cow
lvcreate    Loading vg1-lv_root_snapshot-cow table (252:3)
lvcreate    Resuming vg1-lv_root_snapshot-cow (252:3)
lvcreate    Loading vg1-lv_root_snapshot table (252:1)
lvcreate    Suspending vg1-lv_root (252:0) with filesystem sync with device flush

I tried it several times, and the system always stop at this point. When I execute the same command manually in a shell no change. Stop.
Redirecting the lvremove command on a shell in the same manner is working fine:

lvremove -fv /dev/vg1/lv_root_snapshot >> /var/log/update.log 2>&1
system continues running.

lvcreate manually in a shell and only redirecting stdout is working fine:

lvcreate -v -L 45G -n lv_root_snapshot -s vg1/lv_root >> /var/log/update.log
system continues running

Only the combination of redirecting stdout and stderr to the logfile stops the system completely:
lvcreate -v -L 45G -n lv_root_snapshot -s vg1/lv_root >> /var/log/update.log 2>&1

Any ideas ?

my system:

SLES 11 SP3 64bit
vm58820-6:~ # lvm version
  LVM version:     2.02.98(2) (2012-10-15)
  Library version: 1.03.01 (2011-10-15)
  Driver version:  4.23.0
1 lv for the root-directory, /boot is a "real" partition
1pv, 1 vg


Bernd Lentes

Institut für Entwicklungsgenetik
Gebäude 35.34 - Raum 208
HelmholtzZentrum münchen
bernd.lentes at helmholtz-muenchen.de
phone: +49 89 3187 1241
fax:   +49 89 3187 2294

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