CentOS 7.x Tip: CentOS 7 DO NOT have /usr on separate partition

Just a heads up tip for CentOS 7 dedicated servers when partitioning your disk drives to not partition /usr as a separate partition. You can run it all sorts of problems with systemd D-Bus failures causing all weird stuff.

CentOS 7 on VPSes usually have a large single / partition so don't run into this. OVH CentOS 7 dedicated I didn't separate /usr partition.

Details at separate-usr-is-broken

some errors I have come across like

Code (Text):

journalctl -u dbus --no-pager
-- Logs begin at Sun 2017-05-28 22:28:18 PDT, end at Wed 2017-05-31 01:48:45 PDT. --
May 28 22:28:22 HOST.DOMAIN.COM systemd[1]: Started D-Bus System Message Bus.
May 28 22:28:22 HOST.DOMAIN.COM systemd[1]: Starting D-Bus System Message Bus...
May 28 22:28:22 HOST.DOMAIN.COM dbus-daemon[1366]: dbus[1366]: [system] Activating via systemd: service name='org.freedesktop.timedate1' unit='dbus-org.freedesktop.timedate1.service'
May 28 22:28:22 HOST.DOMAIN.COM dbus[1366]: [system] Activating via systemd: service name='org.freedesktop.timedate1' unit='dbus-org.freedesktop.timedate1.service'
May 28 22:28:22 HOST.DOMAIN.COM dbus[1366]: [system] Successfully activated service 'org.freedesktop.timedate1'
May 28 22:28:22 HOST.DOMAIN.COM dbus-daemon[1366]: dbus[1366]: [system] Successfully activated service 'org.freedesktop.timedate1'
May 28 22:28:56 HOST.DOMAIN.COM systemd[1]: Stopping D-Bus System Message Bus...
May 28 22:28:56 HOST.DOMAIN.COM systemd[1]: Stopped D-Bus System Message Bus.

Code (Text):

crond[30015]: pam_systemd(crond:session): Failed to connect to system bus: Connection refused

Code (Text):

systemctl disable firewalld
Error getting authority: Error initializing authority: Could not connect: Connection refused (g-io-error-quark, 39)

Code (Text):

NetworkManager[1327]: (NetworkManager:1327): GLib-GIO-CRITICAL **: Error while sending AddMatch() message: The connection is closed
NetworkManager[1327]: <warn>  [1495656225.2506] bus-manager: could not create org.freedesktop.DBus proxy (Error calling StartServiceByName for org.freedesktop.DBus: The connection is closed); only the private D-Bus socket will be available

---

 

Reloaded CentOS 7 with partition scheme that doesn't separate /usr partition = no more d-bus failed messages !

This is a cPanel/WHM based dedicated server setup for a paying client

• dual Intel Xeon E5-2620v4
• 64GB ECC DDR4
• 4x1TB Samsung 850 Pro SSD software raid 10 + 1TB Seagate Constellation ES.3 7200RPM SATA
• CentOS 7.3 64bit
• cpanel/WHM
• KernelCare

Code (Text):

df -hT
Filesystem     Type      Size  Used Avail Use% Mounted on
/dev/md126     xfs       1.9T  6.7G  1.9T   1% /
devtmpfs       devtmpfs   32G     0   32G   0% /dev
tmpfs          tmpfs      32G   80K   32G   1% /dev/shm
tmpfs          tmpfs      32G   18M   32G   1% /run
tmpfs          tmpfs      32G     0   32G   0% /sys/fs/cgroup
/dev/md125     xfs       951M  142M  810M  15% /boot
/dev/loop0     ext3      3.9G  8.4M  3.7G   1% /tmp
tmpfs          tmpfs     6.3G     0  6.3G   0% /run/user/0

Code (Text):

/dev/sda
        Model Number:       ST1000NM0033-9ZM173                 
        Firmware Revision:  SN04 
        Transport:          Serial, SATA Rev 3.0
/dev/sdb
        Model Number:       Samsung SSD 850 PRO 1TB             
        Firmware Revision:  EXM03B6Q
        Transport:          Serial, ATA8-AST, SATA 1.0a, SATA II Extensions, SATA Rev 2.5, SATA Rev 2.6, SATA Rev 3.0
/dev/sdc
        Model Number:       Samsung SSD 850 PRO 1TB             
        Firmware Revision:  EXM03B6Q
        Transport:          Serial, ATA8-AST, SATA 1.0a, SATA II Extensions, SATA Rev 2.5, SATA Rev 2.6, SATA Rev 3.0
/dev/sdd
        Model Number:       Samsung SSD 850 PRO 1TB             
        Firmware Revision:  EXM03B6Q
        Transport:          Serial, ATA8-AST, SATA 1.0a, SATA II Extensions, SATA Rev 2.5, SATA Rev 2.6, SATA Rev 3.0
/dev/sde
        Model Number:       Samsung SSD 850 PRO 1TB             
        Firmware Revision:  EXM03B6Q
        Transport:          Serial, ATA8-AST, SATA 1.0a, SATA II Extensions, SATA Rev 2.5, SATA Rev 2.6, SATA Rev 3.0

Code (Text):

df -hT
Filesystem     Type      Size  Used Avail Use% Mounted on
/dev/md126     xfs       1.9T  6.7G  1.9T   1% /
devtmpfs       devtmpfs   32G     0   32G   0% /dev
tmpfs          tmpfs      32G   80K   32G   1% /dev/shm
tmpfs          tmpfs      32G   18M   32G   1% /run
tmpfs          tmpfs      32G     0   32G   0% /sys/fs/cgroup
/dev/md125     xfs       951M  142M  810M  15% /boot
/dev/loop0     ext3      3.9G  8.4M  3.7G   1% /tmp
tmpfs          tmpfs     6.3G     0  6.3G   0% /run/user/0

Xeon E5-2620v4 are 2.1Ghz base clock (2099Mhz) with >6 core utilisation Turbo Boost to 2.5Ghz, 4 core at 2.7Ghz, 1-2 core at 3.0Ghz and idle at 1.2Ghz

Code (Text):

Cpu speed from cpuinfo 2099.00Mhz
True Frequency (without accounting Turbo) 2099 MHz

Socket [0] - [physical cores=8, logical cores=16, max online cores ever=8]
  CPU Multiplier 21x || Bus clock frequency (BCLK) 99.95 MHz
  TURBO ENABLED on 8 Cores, Hyper Threading ON
  Max Frequency without considering Turbo 2198.95 MHz (99.95 x [22])
  Max TURBO Multiplier (if Enabled) with 1/2/3/4/5/6 cores is  30x/30x/28x/27x/26x/25x
  Real Current Frequency 1288.49 MHz (Max of below)
        Core [core-id]  :Actual Freq (Mult.)      C0%   Halt(C1)%  C3 %   C6 %  Temp      VCore
        Core 1 [0]:       1199.43 (12.00x)         1    10.2       1    88.7    28      0.7472
        Core 2 [1]:       1288.49 (12.89x)         1    0.138      0    99.8    29      0.8311
        Core 3 [2]:       1241.32 (12.42x)         1    0.495      0    99.4    28      0.7762
        Core 4 [3]:       1199.86 (12.00x)         1    0.21       0    99.8    27      0.7417
        Core 5 [4]:       1199.55 (12.00x)         1    0.325      1    98.5    28      0.7461
        Core 6 [5]:       1199.87 (12.00x)         1    0.145      0    99.8    27      0.7406
        Core 7 [6]:       1199.40 (12.00x)         1    0.438      0    99.5    28      0.7422
Socket [1] - [physical cores=8, logical cores=16, max online cores ever=8]
  CPU Multiplier 21x || Bus clock frequency (BCLK) 99.95 MHz
  TURBO ENABLED on 8 Cores, Hyper Threading ON
  Max Frequency without considering Turbo 2198.95 MHz (99.95 x [22])
  Max TURBO Multiplier (if Enabled) with 1/2/3/4/5/6 cores is  30x/30x/28x/27x/26x/25x
  Real Current Frequency 1453.82 MHz (Max of below)
        Core [core-id]  :Actual Freq (Mult.)      C0%   Halt(C1)%  C3 %   C6 %  Temp      VCore
        Core 1 [8]:       1270.66 (12.71x)         1       0       1    98.5    33      0.7362
        Core 2 [9]:       1231.09 (12.32x)         1    2.97       0      97    34      0.7401
        Core 3 [10]:      1223.28 (12.24x)         1    6.53       1    92.4    33      0.7349
        Core 4 [11]:      1243.90 (12.44x)         1    12.3       0    87.7    33      0.7384
        Core 5 [12]:      1199.26 (12.00x)         1    1.74       0    98.2    33      0.7346
        Core 6 [13]:      1232.04 (12.33x)         1    1.12       0    98.8    32      0.7341
        Core 7 [14]:      1219.54 (12.20x)         1    3.01       0      97    32      0.7439
        Core 8 [15]:      1453.82 (14.55x)         1    2.94       0      97    32      0.7766