Ceph入门到精通-CrushMap算法概述

下面是伪代码object到osd的伪代码

locator =object_name

obj_hash =hash(locator)

pg =obj_hash %num_pg

OSDs_for_pg =crush(pg) # returns a list of OSDs

primary =osds_for_pg[0]

replicas =osds_for_pg[1:]

defcrush(pg):

all_osds=['osd.0','osd.1','osd.2',...]

result=[]

# size is the number of copies; primary+replicas

whilelen(result)<size:

r=hash(pg)

chosen=all_osds[r%len(all_osds)]

ifchoseninresult:

# OSD can be picked only once

continue

result.append(chosen)

returnresult

CRUSH READ

对于Ceph 集群的一次读写操作，客户端首先联系Ceph 的momtor 并获取一个集群

map 副本。集群map 帮助客户端获取Ceph 集群的状态和配置信息。使用对象和池名IID将数据转换为对象。然后将对象和