July 2016 – Shaun Yuan

July 18, 2016August 2, 2016Others

import Ubuntu 16.04 image into cobbler

if you got this error when you import Ubuntu 16.04 server image into cobbler using cobbler import command, received on stderr: No signature matched in /var/www/cobbler/ks_mirror/Ubuntu-16.04-x86_64 !!! TASK FAILED !!!

July 13, 2016August 3, 2016Kernel

Determine whether a directory is empty or not for ext2 file system

How do we determine whether a directory is empty or not for ext2 file system? first,let’s take a look at a implementation in linux kernel(2.6.11):

July 11, 2016August 2, 2016openstack

Openstack 性能优化之MySQL(MariaDB)

对于openstack的性能优化有很多方面，这里只对mysql也就是mariadb进行简单优化。对于mysql的默认配置，用作小型站点尚且可以运作。但是对于数据中心的环境，使用mysql的默认配置绝对是不行的。我做了个测试，使用默认的配置，用benchmark测试读时，每秒是1600多个事务，但是优化之后，可以达到六千多个，速度提升六倍。文末或有测试数据。这里只讨论几个核心的关键的参数，mysql的参数太多，完全掌握得话大量的时间和精力。 1, default_storage_engine