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[Samba] CTDB potential locking issue




Hi All

I have a newly implemented two node CTDB cluster running on CentOS 7, Samba
4.7.1

The node network is a direct 1Gb link

Storage is Cephfs

ctdb status is OK

It seems to be running well so far but I'm frequently seeing the following
in my log.smbd:

[2018/09/18 19:16:15.897742,  0]
> ../source3/lib/dbwrap/dbwrap_ctdb.c:1207(fetch_locked_internal)
>   db_ctdb_fetch_locked for /var/lib/ctdb/locking.tdb.1 key
> DE0726567AF1EAFD4A741403000100000000000000000000, chain 3642 needed 16
> attempts, 315 milliseconds, chainlock: 78.340000 ms, CTDB 236.511000 ms
> [2018/09/18 19:16:15.958368,  0]
> ../source3/lib/dbwrap/dbwrap_ctdb.c:1207(fetch_locked_internal)
>   db_ctdb_fetch_locked for /var/lib/ctdb/locking.tdb.1 key
> DE0726567AF1EAFD4A741403000100000000000000000000, chain 3642 needed 15
> attempts, 297 milliseconds, chainlock: 58.532000 ms, CTDB 239.124000 ms
> [2018/09/18 19:16:18.139443,  0]
> ../source3/lib/dbwrap/dbwrap_ctdb.c:1207(fetch_locked_internal)
>   db_ctdb_fetch_locked for /var/lib/ctdb/locking.tdb.1 key
> DE0726567AF1EAFD4A741403000100000000000000000000, chain 3642 needed 11
> attempts, 128 milliseconds, chainlock: 27.141000 ms, CTDB 101.450000 ms
>

Can someone advise what this means and if it's something to be concerned
about?

I've worked with ctdb set-ups in the past and don't recall seeing these
messages but that could just be because verbosity is higher with this
version.

It's a new implementation, I've not had any performance or locking issues
reported and smbstatus -L looks normal although have noticed load average
on servers are a little higher than expected

Here is my sanitized smb.comf and ctdbd.conf:

[global]
   workgroup = DOMAIN
   realm = DOMAIN.LOCAL
   security = ADS
   clustering = yes
   idmap config * : range = 16777216-33554431
   template shell = /bin/false
   kerberos method = secrets only
   winbind use default domain = True
   netbios name = HOSTNAME
   log level = 1
   create krb5 conf = yes
   encrypt passwords = yes
   unix extensions = No
   min protocol = smb2
   max protocol = smb2
   strict allocate = yes
   follow symlinks = yes
   allow insecure wide links = yes
   idmap config DOMAIN : backend = ad
   idmap config DOMAIN : range = 700-199999
   idmap config DOMAIN : schema_mode = rfc2307
   idmap config DOMAIN : unix_nss_info = yes
   idmap config DOMAIN:unix_primary_group = yes
   winbind enum users = yes
   winbind enum groups = yes
   winbind normalize names = no
   winbind reconnect delay = 2
   winbind cache time = 900
   name resolve order = host
   disable netbios = yes
   fileid:algorithm = fsid
   vfs objects = fileid
   usershare allow guests = yes
   map to guest = Bad User
   hide dot files = Yes
   hide files = /$*/
   hide special files = yes
   strict sync = No

/etc/ctdb/ctdbd.conf:

 CTDB_PUBLIC_ADDRESSES=/etc/ctdb/public_addresses
 CTDB_MANAGES_SAMBA=yes
 CTDB_SAMBA_SKIP_SHARE_CHECK=yes
 CTDB_MANAGES_WINBIND=yes
 CTDB_MANAGES_NFS=yes
 CTDB_NFS_CALLOUT=/etc/ctdb/nfs-ganesha-callout
 CTDB_NFS_CHECKS_DIR=/etc/ctdb/nfs-checks-ganesha.d
 CTDB_NFS_SKIP_SHARE_CHECK=yes
 CTDB_DEBUGLEVEL=NOTICE
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