grub2-install: error: disk `mduuid/e54081d398c6d57b4d67436f6d032162' not found

After raid 1 disk replacement faced with this issue

# grub2-install /dev/sdb

Installing for i386-pc platform.

grub2-install: error: disk `mduuid/e54081d398c6d57b4d67436f6d032162' not found.

Rabbitmq create user

# Enable web interface plugin
rabbitmq-plugins enable rabbitmq_management

# Create user with password
rabbitmqctl add_user megaadmin zwuvY0Ce7AETPsY2t4v5

# Set user role
rabbitmqctl set_user_tags megaadmin administrator
# Set user permissions
rabbitmqctl set_permissions -p / megaadmin ".*" ".*" ".*"

PPTP issues

Issue:

Mar 20 19:05:00 ct pppd[1362]: LCP: timeout sending Config-Requests
Mar 20 19:05:00 ct pppd[1362]: Connection terminated.
Mar 20 19:05:00 ct pppd[1362]: Modem hangup
Mar 20 19:05:00 ct pptp[1363]: anon warn[decaps_hdlc:pptp_gre.c:217]: short read (-1): Input/output error
Mar 20 19:05:00 ct pptp[1363]: anon warn[decaps_hdlc:pptp_gre.c:229]: pppd may have shutdown, see pppd log
Mar 20 19:05:00 ct pptp[1376]: anon log[callmgr_main:pptp_callmgr.c:242]: Closing connection (unhandled)
Mar 20 19:05:00 ct pptp[1376]: anon log[ctrlp_rep:pptp_ctrl.c:254]: Sent control packet type is 12 'Call-Clear-Request'
Mar 20 19:05:00 ct pptp[1376]: anon log[call_callback:pptp_callmgr.c:81]: Closing connection (call state)

Resolution:

# modprobe nf_conntrack_proto_gre

# modprobe ip_gre

# modprobe nf_conntrack_pptp

Error: Package: libprlcommon-7.0.194-1.vz7.x86_64 (factory)

To fix error with openvz installation

Error: Package: libprlcommon-7.0.194-1.vz7.x86_64 (factory)
           Requires: libjson-c.so.2(libjson-c.so.2)(64bit)
Error: Package: ploop-7.0.183-1.vz7.x86_64 (factory)
           Requires: libjson-c.so.2(libjson-c.so.2)(64bit)
Error: Package: 1:libguestfs-1.40.2-5.1.vz7.6.x86_64 (factory)
           Requires: libjansson.so.4(libjansson.so.4)(64bit)
 You could try using --skip-broken to work around the problem
 You could try running: rpm -Va --nofiles --nodigest

Need to install these packages

yum install http://repo.virtuozzo.com/vzlinux/7.7/x86_64/os/Packages/j/jansson-2.10-1.vl7.1.x86_64.rpm
yum install http://repo.virtuozzo.com/vzlinux/7.7/x86_64/os/Packages/j/json-c-0.11-13.vl7.1.x86_64.rpm

How to install OpenVZ 7 to CentOS 7 server

Install OpenVZ kernel

1. Go to https://download.openvz.org/virtuozzo/releases/ and choose latest OpenVZ release, in my case this is openvz-7.0.7-359 release
And install python-subprocess package

# yum localinstall https://download.openvz.org/virtuozzo/releases/openvz-7.0.7-359/x86_64/os/Packages/p/python-subprocess32-3.2.7-1.vz7.3.x86_64.rpm

And OpenVZ release package
# yum localinstall yum localinstall https://download.openvz.org/virtuozzo/releases/openvz-7.0.7-359/x86_64/os/Packages/o/openvz-release-7.0.7-1.vz7.x86_64.rpm

And install openvz kernel with necessary packagges
# yum install prlctl prl-disp-service vzkernel ploop ploop-lib python-ploop --nogpgcheck


Then need to change default boot kernel

# awk -F\' /^menuentry/{print\$2} /etc/grub2.cfg
Virtuozzo 7 (3.10.0-693.21.1.vz7.50.2)
CentOS Linux (3.10.0-862.2.3.el7.x86_64) 7 (Core)
CentOS Linux (0-rescue-9063ac396d784f4c997ceacdd0590c25) 7 (Core)

Sort starts from 0, in my case need to execute 

# grub2-set-default 0

And check result

# cat /boot/grub2/grubenv |grep saved

saved_entry=Virtuozzo 7 (3.10.0-693.21.1.vz7.50.2)

And last step - rebuild grub config

grub2-mkconfig -o /boot/grub2/grub.cfg

Now you can reboot server 

Tested on CentOS Linux release 7.5.1804 (Core) 

Grafana reset password

1. Install sqlite3
2. sqlite3 /var/lib/grafana/grafana.db

3.
update user set password = '59acf18b94d7eb0694c61e60ce44c110c7a683ac6a8f09580d626f90f4a242000746579358d77dd9e570e83fa24faa88a8a6', salt = 'F3FAxVm33R' where login = 'admin';

And now you can login as user and password "admin" 

Linux top opened files

## Get common list of all opened files
lsof > lsof.log

## Get top
cat lsof.log | awk '{ print $2 " " $1; }' | sort -rn | uniq -c | sort -rn | head -20