第一部分

介绍共享存储和fc存储

共享存储介绍

共享存储实现了,cpu/内存与存储设备的分离

存储的属性

存储的属性由capacity(容量)和performance(性能)两个方面来度量.

容量:就是能够存储数据的多少(gigabit)

性能:可以从三个方面进行测量

1.bandwidth(mb per second or mbps)带宽

2.throughput(i/o persecond or iops)吞吐量:输入输出操作,随机i/o,大容量i/o,小容量i/o.每秒接收多少i/o操作.

3.latency(in milliseconds)延时

raid介绍

raid schemes embrace this by leveraging multiple disks together and using copies of data to support i/o until the drive can be replaced and the raid protection can be rebuilt.each raid configuration tends to have different performance characteristics and different capacity overhead impact

(重点:提高速度(i/o),数据冗余保护,不同的raid技术有不同的性能,和容量消耗)raid0

raid 0 this raid level offers no redundancy and no protection against drive failure.in fact,it has a higher aggregate risk than a  single disk because any single disk failing affects the whole raid group.(重点:提高了速度,没有冗余,没有保护,任何一块硬盘出现问题,整个raid组的数据全部丢失)

raid1,10(镜像raid)

raid1 these "mirrored" raid levels offer high degrees of protection but at the cost of 50 percent loss of usable capacity,raid 1 simply writes every i/o to two drives and can balance reads across both drives(since there are two copies),this can be coupled with raid 0 or with raid 1+0（or raid 10),(重点:强的数据保护,但是50%容量的消耗)

raid5,6

raid5 these raid levels use a mathematical calculation (an xor parity calculation)to represent the data across several drives.this tends to be a good compromise between the availability of raid 1 and the capacity efficiency of raid 0.(重点:强的数据保护,较小的容量消耗)

raid5只能容忍一块盘坏掉,才能恢复数据.所有硬盘不同条带,校验和位置不同,如果校验和在同一个硬盘是raid3.

raid6第一块盘的值是校验和数据,加上其他参数校验和的值是第二块硬盘数据.任何两块硬盘坏了,都是可以恢复的.不同条带校验和也是随机的.

关于sans

sans are most commonly associated with fibre channel storage,because fibre channel was the first protocol type used with sans.however,san refers to a network topology,not a connection protocol.although people often use the acronym san to refer to a fibre channel san,it is completely possible to create a san topology using different types of protocols,including iscsi,fcoe,and infiniband.

sans were initally deployed to mimic the characteristics of local or direct attached scsi devices.a san is a network where storage devices(logical units-or luns-just like on a scsi or sas controller)are presented from a storage target(one or more ports on an array)to one or more initiators.an initiator is usually a host bus adapter(hba)or converged network adapter(cna),though software-based initiators are available for iscsi and fcoe.

esxi支持的存储选项

1.fibre channel

2.fibre channel over ethernet

3.iscsi using software and hardware initiators

4.nas(specifically,nfs)

5.local sa/sata/scsi storage

6.infiniband

fibre channel术语

fibre channel hba:host bus adapters,most including adapters from both qlogic and emulex vendor.

wwn:all the objects(initiators,targets,and luns)on a fibre channel san are identified by a unique 64-bit identifier called a worldwide name(wwn).wwns can be worldwide port names(a port on a switch）or node names(a port on an endpoint).

the fibre channel protocol can operate in three modes:point-to-point(fc-p2p),arbitrated loop(fc-al),and switched(fc-sw)

the most common fibre channel configuration:a switched fibre channel(fc-sw)san.

vsphere5.0物理拓扑