Categories
poem

使用virsh执行qemu-monitor命令

virsh 可以发送命令给qemu-monitor

virsh # help  qemu-monitor-command host
  NAME
    qemu-monitor-command - QEMU Monitor Command

  SYNOPSIS
    qemu-monitor-command <domain> [--hmp] [--pretty] {[--cmd] <string>}...

  DESCRIPTION
    QEMU Monitor Command

  OPTIONS
    [--domain] <string>  domain name, id or uuid
    --hmp            command is in human monitor protocol
    --pretty         pretty-print any qemu monitor protocol output
    [--cmd] <string>  command

Categories
poem

快照与备份的区别

定义

SNIA对快照的描述:

A point in time copy of a defined collection of data.

快照有全量快照和增量快照.我们常用的基本是增量快照(delta snapshot)

A type of point in time copy that preserves the state of data at an instant in time,
by storing only those blocks that are different from an already existing full copy of the data.

主要特点是,快照是虚拟的拷贝而不是物理的拷贝,只有发生过修改的block才会被重写.因此如果完全没有被修改过的块遭遇破坏而导致的存储错误.快照回滚也无法修复.

目的

做快照,通常有2个目的:
+ 一是为了将来对于删除或损坏的文件能够进行恢复
+ 二是作为副本或备份的源端(防止快照发生物理介质性质的损坏)

Categories
poem

见与不见

/*
你爱或者不爱我
爱就在那里
不增不减
*/
while( you.love(me) || !you.love(me) ){
    me.emotion.love.value++;
    me.emotion.love.value--;
}
                            **--苍央嘉措**