The Problem System cannot proceed with the boot process, stuck with an error messages: systemd-udevd[369]: fork of '/bin/sh -c '>/tmp/.lvm_scan-sdc;'' failed: Cannot allocate memory A start job is running for dev-mapper-\x2droot.device The Solution If the systemd unit called lvmetad is enabled and running, the metadata is cached which reduces disk scanning and it provides LVM commands with VG metadata and PV state. LVM commands will then avoid reading the information from disks. If there … [Read more...] about “systemd-udevd: Cannot Allocate Memory” and “A start job is running for dev-mapper-\x2droot.device” – CentOS/RHEL 7 booting issue
CentOS/RHEL
“Device /dev/mappper/mpath25 Not Found (or Ignored By Filtering)” – error while creating physical volume with pvcreate
The Problem When trying to create physical volume , getting the below error error: # pvcreate /dev/mappper/mpath25 Device /dev/mappper/mpath25 not found (or ignored by filtering). The issue can be reproduced at will with the following step: # pvcreate /dev/mappper/mpath25 The Solution Upon checking it was found that start sector was not zeroed out. # pvcreate /dev/mappper/mpath25 Device /dev/mappper/mpath25 not found (or ignored by filtering). # fdisk -l … [Read more...] about “Device /dev/mappper/mpath25 Not Found (or Ignored By Filtering)” – error while creating physical volume with pvcreate
“Read-only locking type set. Write locks are prohibited. Can’t get lock for [volume group]” – error during lvextend
The Problem Unable to extend LVM filesystem. The following error message is received on running the lvextend command: Read-only locking type set. Write locks are prohibited. Can't get lock for rootvg resize2fs 1.43-WIP (20-Jun-2013) The filesystem is already 1310720 blocks long. Nothing to do! The Solution The parameter locking_type is set to 4 in /etc/lvm/lvm.conf. # grep locking lvm.conf |grep -v '#' "lvmetad", "metadata", "cache", "locking" ] locking_type = 4 … [Read more...] about “Read-only locking type set. Write locks are prohibited. Can’t get lock for [volume group]” – error during lvextend
“dracut-initqueue[286]: Warning: dracut initqueue timeout – starting timeout scripts” – CentOS/RHEL 7 booting issue
The Problem Messages "dracut-initqueue timeout - starting timeout scripts" are printed loop while booting then an Emergency shell is launched: dracut-initqueue[]: Warning: dracut initqueue timeout - starting timeout scripts dracut-initqueue[]: Warning: dracut initqueue timeout - starting timeout scripts dracut-initqueue[]: Warning: dracut initqueue timeout - starting timeout scripts dracut-initqueue[]: Warning: dracut initqueue timeout - starting timeout scripts dracut-initqueue[]: … [Read more...] about “dracut-initqueue[286]: Warning: dracut initqueue timeout – starting timeout scripts” – CentOS/RHEL 7 booting issue
“Failed to Start Activation of LVM2 Logical Volumes” and “Unit lvm2-activation-net.service Entered Failed State” – CentOS/RHEL 7 booting issue
The Problem System cannot boot-up properly with below logs: [ OK ] Started File System Check on /dev/xvdd. [ OK ] Started File System Check on /dev/xvdg. [ OK ] Started File System Check on /dev/xvdb. [ OK ] Started File System Check on /dev/xvdc. [ OK ] Started File System Check on /dev/disk/by-label/BOOT. Mounting /boot... [ OK ] Mounted /boot. [FAILED] Failed to start LVM2 PV scan on device 202:65. See 'systemctl status lvm2-pvscan@202:65.service' for details. [FAILED] Failed to … [Read more...] about “Failed to Start Activation of LVM2 Logical Volumes” and “Unit lvm2-activation-net.service Entered Failed State” – CentOS/RHEL 7 booting issue
“WARNING: Failed to connect to lvmetad. Falling back to device scanning” – error while running LVM commands
The Problem The LVM commands showing below errors: # pvs WARNING: Failed to connect to lvmetad. Falling back to device scanning. >>>> Masked Active: inactive (dead) Sep 08 20:34:29 systemd[1]: Cannot add dependency job for unit lvm2-lvmetad.socket, ignoring: Unit is masked. Sep 08 20:34:32 systemd[1]: Cannot add dependency job for unit lvm2-lvmetad.socket, ignoring: Invalid request descriptor Sep 08 20:34:38 systemd[1]: Cannot add dependency job for unit lvm2-lvmetad.socket, … [Read more...] about “WARNING: Failed to connect to lvmetad. Falling back to device scanning” – error while running LVM commands
CentOS/RHEL: “id” command doesn’t list the Group Name against GID for LDAP Users
The Problem While running "id" command against LDAP users, it only displays the gid for some secondary group and the group name is not being printed: # id user1 uid=48254(user1) gid=100(users) groups=100(users),5002(group1),5001(group2),41257(group3),856(group4),56971 And, the below error was logged in /var/log/sssd/sssd_nss.log : (Tue Mar 14 05:40:09 2020) [sssd[nss]] [nss_cmd_getgrgid_search] (0x0010): getgrgid call returned more than one result !?! The Solution The new group was … [Read more...] about CentOS/RHEL: “id” command doesn’t list the Group Name against GID for LDAP Users
Windows Active Directory Account Shows Inconsistent UID/GID In Different Linux SSSD Clients (CentOS/RHEL)
The Problem The id command shows different UID and GID on different sssd servers for the same Windows Active Directory user. After purging the sssd cache by sss_cache, the UID and GID are still different. 1. Output from one server: # id ad_test_user uid=[UID](ad_test_user) gid=[GID](ad_test_group) groups=[GID](ad_test_group2),[GID](ad_test_group) # sss_cache -u ad_test_user # id ad_test_user uid=[UID](ad_test_user) gid=[GID](ad_test_group) … [Read more...] about Windows Active Directory Account Shows Inconsistent UID/GID In Different Linux SSSD Clients (CentOS/RHEL)
How To Create A SSH Banner in CentOS/RHEL Server
Note: Please do not put any classified information in a banner file since banner message is displayed before entering user/password credential during ssh/scp session. 1. Create the text file that should appear as the warning. For example /etc/sshbanner.txt: [root@server]# vi /etc/sshbanner.txt ############################################################################################################################################################### # # WARNING TO USERS OF THIS … [Read more...] about How To Create A SSH Banner in CentOS/RHEL Server
Error: Can’t open display: hostname:x.y when running xclock
The Problem Unable to launch xclock window using the below command for one particular normal user. xclock is fine with the root user. $ xclock Error: Can't open display: [hostname]:x.y The Solution Incorrect user level environment variables set under the file /home/[username]/.bash_profile. Follow the below steps to fix the issue. 1. Log in as a normal user. 2. Comment out all the user specific env variables under the file /home/[username]/.bash_profile. 3. Launch VNC … [Read more...] about Error: Can’t open display: hostname:x.y when running xclock