How to fix "NoValidHost: No valid host was found. There are not enough hosts available" during overcloud deployment (openstack)

How to fix "NoValidHost: No valid host was found. There are not enough hosts available" during overcloud deployment (openstack)

Error: NoValidHost: No valid host was found You get below error message on the console while performing an overcloud deployment from the undercloud director 2018-08-14 06:42:59Z [overcloud.Controller.0.Controller]: CREATE_FAILED  ResourceInError: resources.Controller: Went to status ERROR due to "Message: No valid host was found. There are not enough hosts available., Code: 500" 2018-08-14 06:42:59Z [overcloud.Controller.0]: CREATE_FAILED  Resource ... Read more How to fix "NoValidHost: No valid host was found. There are not enough hosts available" during overcloud deployment (openstack)

How to check memory usage of an individual process or application/program in Linux

How to check memory usage of an individual process or application/program in Linux

We know there are various tools available which can help you get the memory related information from the system, some of them are listed below Report short summary of memory utilization statistics. # free Report details of memory utilization statistics. # cat /proc/meminfo Report details of slab utilization statistics. # cat /proc/slabinfo Report virtual memory ... Read more How to check memory usage of an individual process or application/program in Linux

How to enable or disable transparent (THP) and explicit (nr_hugepages) hugepage and check the status in Linux with examples (explained in detail)

How to enable or disable transparent (THP) and explicit (nr_hugepages) hugepage and check the status in Linux with examples (explained in detail)

Below list of topics are covered in this article: Types of HugePages How to disable Transparent Hugepages on runtime How to disable Transparent Hugepages permanently using GRUB2 How to disable Transparent Hugepages permanently using tuned profile Use your existing tuned profile Create a new customised tuned profile How to check if HugePages is disabled How ... Read more How to enable or disable transparent (THP) and explicit (nr_hugepages) hugepage and check the status in Linux with examples (explained in detail)

What is transparent hugepage (THP) and how to check THP usage per process in Linux (Explained)

Hugepages is a feature that allows the Linux kernel to utilise the multiple page size capabilities of modern hardware architectures. Memory is managed in blocks known as pages. A page is 4096 bytes. 1MB of memory is equal to 256 pages; 1GB of memory is equal to 256,000 pages, etc. To get the page size ... Read more What is transparent hugepage (THP) and how to check THP usage per process in Linux (Explained)

How to lock or unlock a root and normal user account using pam_tally2 and pam_faillock after certain number of failed login attempts in Linux

How to lock or unlock a root and normal user account using pam_tally2 and pam_faillock after certain number of failed login attempts in Linux

Below list of topics will be covered in this article Lock account using pam_tally2 Lock non-root user (normal user) for failed login attempts Lock "root" user for failed login attempts Unlock non-root (normal) user account using pam_tally2 Unlock "root" user account using pam_tally2 Lock account using pam_faillock Lock non-root user using pam_faillock for 3 failed ... Read more How to lock or unlock a root and normal user account using pam_tally2 and pam_faillock after certain number of failed login attempts in Linux

How to check the swap memory usage by a process in Linux

How to check the swap memory usage by a process in Linux

Earlier I had written an article on swappiness and different commands to check memory usage per process on Linux here I will show you some of the methods which can be used to check the swap memory utilisation. Below article is tested and validated on Red Hat Enterprise Linux 7. IMPORTANT NOTE:  There is no way ... Read more How to check the swap memory usage by a process in Linux