[linux-lvm] problem with lvcreate and redirection

[Zdenek Kabelac]

Dne 19.2.2016 v 19:40 Lentes, Bernd napsal(a):
> Hi,
>
> i have a script in which i invoke lvremove and lvcreate. With lvremove i don't have proplems but with lvcreate.
> I'm redirecting stdout and stderr to a file because the script is executed by cron and i'd like to have a look afterwards if everything went fine.
> The command is: lvcreate -v -L 25G -n lv_root_snapshot -s vg1/lv_root > lvcreate_with_redirection.log 2>&1. Shell does not accept further commands afterwards, but host still responds to ping. You can have a look on lvcreate_with_redirection.log here: https://hmgubox.helmholtz-muenchen.de:8001/d/b4c7025bac/ .
> System seems to stop while suspending.
>
> last lines of the log:
> ======================================================
>
> ...
>      Creating vg1-lv_root_snapshot-cow
>      Loading vg1-lv_root_snapshot-cow table (252:3)
>      Resuming vg1-lv_root_snapshot-cow (252:3)
>      Loading vg1-lv_root_snapshot table (252:1)
>      Suspending vg1-lv_root (252:0) with filesystem sync with device flush
> ======================================================
>


Unfortunately you can't do that if you log to the SAME volume you are 
suspending - i.e. you run your command from your root volume
which is also suspended.

We could likely 'buffer' the output while in suspend mode,
and throw out the output later - but as this is seen as 'debug' help it's 
assume user takes care and user place for logging which doesn't block.

So if you want to see logs - use something tmpfs location for it.

Regards


Zdenek