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1. Mount Ceph block disk of a server instance.

   Get the block device from vm

   root@overcloud-compute-01:~# virsh domblklist instance-00000001
   Target     Source
   ------------------------------------------------
   vda        compute/f0984ae9-f9c9-439b-80b9-f1c6201c914c_disk
   

   Shutdown the instance from OSP

   Map the disk using rbd command

   root@overcloud-compute-01:~# rbd map compute/f0984ae9-f9c9-439b-80b9-f1c6201c914c_disk --name client.admin
   

   Mount the disk

   root@overcloud-compute-01:~# mount /dev/rbd/compute/f0984ae9-f9c9-439b-80b9-f1c6201c914c_disk-part1 /mnt
   

   Do the changes …

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2. A simple bash script bot to send status message to telegram.

   The telegram bot script

   Here is a simple telegram bot script I have used to send out OpenStack deployment status message to my telegram.

   1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 …

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3. egrep Regex for filtering mac

   egrep Regex

   '([0-9a-f]{2}:){5}[0-9a-f]{2}'
   

   Example

   for i in $(virsh list |grep -v Name|awk '{print $2}' ) ; do 
      echo -e $i 
      virsh domiflist $i
   done | egrep '([0-9a-f]{2}:){5}[0-9a-f]{2}' | awk '{print $NF}'
   

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4. Usefull utility to Control bandwidth

   Useful utility to control bandwidth.

   tc is a useful utility to control bandwidth and to simulate long distance links Here is the man page https://linux.die.net/man/8/tc

   Example

   Thanks to Taco (my collegue) for the tip

   tc qdisc add dev eth0 root netem delay 100ms
   

   For …

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5. Recover from Pacemaker resource management disabled .

   The error message

            *** Resource management is DISABLED ***
   The cluster will not attempt to start, stop or recover services
   

   Get cluster out of maintenance mode

   pcs property unset maintenance-mode
   

   To start the pacemaker cluster

   pcs cluster start --all
   

   Referrence and Thanks

   https://www.cloudatoz.com/openstack-resource-management-is-disabled/

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6. How to download images from OpenStack Glance.

   Here is the syntax to download images from OpenStack glance

   source overcloudrc
   openstack image save --file local-file-name.qcow2 image-name
   

   Or if you would like to compress the downloaded image on the fly

   source overcloudrc
   openstack image save image-name | gzip -c > local-file-name.raw.gz
   

   Example

   [stack@ospdir ~]$ source overcloudrc
   (admin@overcloud …

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