[Samba] CTDB and locking issues reloaded
Giuseppe Lo Presti
Giuseppe.LoPresti at cern.ch
Wed Apr 15 08:59:29 UTC 2020
Hi there,
I'm following your list for several months, as we run a CTDB cluster of
Samba gateways over our distributed filesystem. I decided to post my
first message to resume an old thread
(https://lists.samba.org/archive/samba/2016-October/204043.html), hoping
to progress and reach some conclusion.
Essentially, we observe and can reproduce issues when attempting to lock
a given file from two clients connecting to two DIFFERENT samba
gateways, whereas everything works as expected when the two clients
happen to connect to the same samba gateway.
The issue is that both clients are able to take an exclusive lock on the
same file, as if the lock information is not propagated across the
cluster. And indeed I could see the following on the server side:
# smbstatus -L | grep lopresti
2:8324 4179 DENY_ALL 0x3 RDWR NONE /eos home-l/lopresti/testsambalock
Tue Apr 14 12:00:45 2020
3:29245 4179 DENY_ALL 0x3 RDWR NONE /eos home-l/lopresti/testsambalock
Tue Apr 14 12:02:38 2020
I obtained the above by patching the smbclient code from a 4.12 branch
following the above mentioned thread, and starting two separate sessions as:
$ ./bin/smbclient //128.142.32.44/eos
smb: \> cd home-l/lopresti
smb: \home-l\lopresti\> open testsambalock
open file \home-l\lopresti\testsambalock: for read/write fnum 1
and:
$ ./bin/smbclient //128.142.32.45/eos
smb: \> cd home-l/lopresti
smb: \home-l\lopresti\> open testsambalock
open file \home-l\lopresti\testsambalock: for read/write fnum 1
[The IPs being two of the four public IPs of our cluster]
The servers are running Samba 4.9.1-10 on CentOS 7.7. Locking settings
are as follows:
# grep lock /etc/samba/smb.conf
locking = yes
posix locking = no
strict locking = no
oplocks = no
level2 oplocks = no
kernel oplocks = no
We've tried different combinations for the locking settings, following
different (even contradicting) advices, but nothing changed with respect
to this issue.
So the question is do you acknowledge the correct behaviour should be to
prevent the second client from getting the lock? What would you advice
as locking settings?
To further debug the case, I've collected full (level 10) logs of the
two sessions on the two gateways, and can make them available, as well
as the full configuration or anything else you may need.
Thanks in advance for your help,
Cheers,
Giuseppe
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