fio disk benchmark

fio --name=rand-write --ioengine=libaio --iodepth=32 --rw=randwrite --invalidate=1 --bsrange=4k:4k,4k:4k --size=512m --runtime=120 --time_based --do_verify=1 --direct=1 --group_reporting --numjobs=1

Nginx: zwracanie 444 przy próbie odwołania do nieistniejących hostów

server {
  server_name _;
  listen 80 default_server;
  return 444;
}

server {
  server_name _;
  listen 443 default_server;
  return 444;
}

find: znajdź i przenieś

find . -name "*.bak" -print0 | xargs -0 -I {} mv {} ~/old.files

MegaRAID smartd

megacli -pdlist -a0| grep 'Device Id'

Device Id: 0
Device Id: 1

smartctl -d sat+megaraid,1 -a /dev/sda

smartd.conf

/dev/sda -d megaraid,00 -H -W 1 -m MAIL -M exec /usr/share/smartmontools/smartd-runner
/dev/sda -d megaraid,01 -H -W 1 -m MAIL -M exec /usr/share/smartmontools/smartd-runner

CentOS: Error: rpmdb open failed

rm -f /var/lib/rpm/__db*
db_verify /var/lib/rpm/Packages
rpm --rebuilddb
yum clean all

Ubuntu: GRUB Error 17 / OVH

root (hd0,0)
setup (hd0)
kernel /boot/vmlinuz-XXXX root=/dev/vda1
initrd /boot/initrd.img-XXX
boot

OVH KVM resize root parition Centos 7 XFS

lsblk

parted

select /dev/sdb

unit s

print

rm 1

mkpart

Partition type? primary
File system type? xfs
Start? 2048s
End? 100%

print

set 1 boot on

quit

mount /dev/sdb1 /mnt

xfs_growfs -d /mnt

sentora / zpanel change e-mail quota

mysql;
use sentora_postfix;
update mailbox set quota = 3000 where username like "email@domain.com";

atop cheat sheet

Cron

58 23 * * * killall atop
05 0 * * * rm -f /var/log/atop.log
07 0 * * * atop -w /var/log/atop.log 5

To read the log:

# atop -r /var/log/atop.log

Press t to move forward to the next 5 seconds, and press shift+t to move backwards.

To read only a certain time range from the log (b for beginning, e for end):

# atop -r atop.log -b 10:00 -e 11:00

To change the view:

g - Show generic output (default)

m - Show memory related output

s - Show scheduling characteristics

c - Show the command line of the process

how many inodes in directory

find /path -xdev -printf '%h\n' | sort | uniq -c | sort -k 1 -n