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OEL 7

“Failed to start test.mount: Unit is not loaded properly: Invalid argument.” – While mounting a fileystem using systemd

by admin

The Problem Under /etc/systemd/system the mount unit file was created with name “test.mount”. The mount point directory created is /home/test. Under the mount unit file options in the “Where=” the mount point configured is /home/test. The device where the filesystem will be mounted is /dev/xvdb1 and it was defined under “What=” option. When configuring mount […]

Filed Under: CentOS/RHEL 7, Linux, OEL 7

How to Disable the ‘lvm2-lvmetad.socket/service’ on CentOS/RHEL 7

by admin

Disabling lvm2-lvmetad.socket/service on CentOS/RHEL 7 system works while the system is running, but after a reboot, it comes up again. This post will show you how to prevent this from happening. 1. Modify the /etc/lvm/lvm.conf file with your favorite file editor, like vi or nano, and switch the value of “use_lvmetad = ” from 1 […]

Filed Under: CentOS/RHEL 7, Linux, OEL 7

How To Disable Ksplice Service on OEL

by admin

This post will assist you to disable ksplice service or when ULN registration time enabled this service unknowingly. 1. Login to URL with ULN credentials https://status-ksplice.oracle.com/status/ -> Allow/Deny Policies -> Select your hostname > then choose all or deny. Once denied, cannot do operations with uptrack or ksplice. For example: [root@client ~]# uptrack-upgrade -n This […]

Filed Under: Linux, OEL 6, OEL 7

How to Disable “Predictable Network Interface Device Names” in CentOS/RHEL 7

by admin

On a CentOS/RHEL 7, the network interface will be named like enoxxx. This post provides steps on how to disable such “Predictable Network Interface Device Names”. We can use the following ways to disable the predictable network interfaces: 1. Create your own manual naming scheme by defining your own udev rules file in /etc/udev/rules.d folder […]

Filed Under: CentOS/RHEL 7, Linux, OEL 7

How to Add a 3rd Disk to Create a 3-way Mirror RAID1 MD Device (CentOS/RHEL 7)

by admin

Question: How to create a 3 mirror RAID1 “md” device by adding a 3rd disk to a 2 mirror device? # cat /proc/mdstat Personalities : [raid1] md123 : active raid1 sda4[0] sdb4[1] 204736 blocks super 1.0 [2/2] [UU] bitmap: 0/1 pages [0KB], 65536KB chunk md124 : active raid1 sda1[0] sdb1[1] 524906496 blocks super 1.2 [2/2] […]

Filed Under: CentOS/RHEL 7, Linux, OEL 7

Extend the Size of /boot Partition on XFS Filesystem (CentOS/RHEL 7)

by admin

The scope of this post is to explain the steps involved in increasing the /boot filesystem, where filesystem type is XFS and when no sufficient space available to install a new kernel package. Though we have standard methods to reduce the size of /boot i.e. removing unused kernel and image files from the boot, as […]

Filed Under: CentOS/RHEL 7, Linux, OEL 7

Extend volume on non-partitioned disk (XFS) under VMware guest

by admin

Question: How to extend virtual volume ( guest disk ) under OS which runs lvm2 and xfs on target device which does not use partitions? 1. Create a full Guest system backup. 2. Extend the Guest disk from the VMware layer (from Vsphere). 3. Run below command to detect new size on the guest disk. […]

Filed Under: CentOS/RHEL 6, CentOS/RHEL 7, Linux, OEL 6, OEL 7

“xfs_log_force: error 5 returned” – XFS Error (CentOS/RHEL 7)

by admin

The Problem Found below error messages on the XFS filesystem. kernel: XFS (dm-0): Corruption detected. Unmount and run xfs_repair kernel: XFS (dm-0): xfs_do_force_shutdown(0x8) called from line 1369 of file fs/xfs/xfs_buf.c. Return address = 0xffffffffa01efd4c kernel: XFS (dm-0): Corruption of in-memory data detected. Shutting down filesystem kernel: XFS (dm-0): Please umount the filesystem and rectify the […]

Filed Under: CentOS/RHEL 7, Linux, OEL 7

How to Restrict Active Directory Users and Groups to Login to CentOS/RHEL 7 Client

by admin

Question: How to Restrict AD Users/Group to login to our server (CentOS/RHEL 7). 1. Modify the configuration file /etc/security/access.conf file – the below configuration denies all the other user but allows access from root and testgroup. + : Domain\testgroup : ALL + : root : ALL – : ALL : ALL 2. Add pam_access.so module […]

Filed Under: CentOS/RHEL 7, Linux, OEL 7

Unable to ssh to server after integration into Active Directory (AD) Domain [CentOS/RHEL 7]

by admin

The Problem The CentOS/RHEL 7.3 system was successfully configured to join an Active Directory domain. A user on the OL system cannot login and the following entries are found in the /var/log/messages system log: 2017-06-28T11:28:41.404719-04:00 adclient sshd[10352]: pam_sss(sshd:auth): authentication success; logname= uid=0 euid=0 tty=ssh ruser= rhost=X.X.X.X user=test1 2017-06-28T11:28:41.573420-04:00 adclient sshd[10352]: pam_krb5[10352]: account checks fail for […]

Filed Under: CentOS/RHEL 7, Linux, OEL 7

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