一些关键设备的Latency时间

下面的内容那个来自Jeff Dean在LADIS大会上做的报告.
Designs,Lessons and Advice from Building Large Distributed Systems

Numbers Everyone Should Know

devices	latency
L1 cache reference	0.5 ns
Branch mispredict	5 ns
L2 cache reference	7 ns
Mutex lock/unlock	25 ns
Main memory reference	100 ns
Compress 1K bytes with Zippy	3,000 ns
Send 2K bytes over 1 Gbps network	20,000 ns
Read 1 MB sequentially from memory	250,000 ns
Round trip within same datacenter	500,000 ns
Disk seek	10,000,000 ns
Read 1 MB sequentially from disk	20,000,000 ns
Send packet CA->Netherlands->CA	150,000,000 ns

关于相关设备的吞吐量(throughput)可以参考List of Device bit rates

新增部分磁盘设备的读写效率信息 added 2010-06-04

Product	~IOPS	Capacity
7200 RPM Disk	100	2TB
10K RPM Disk	140	600GB
15K RPM Disk	160	600GB
Fusion-IO Device (SLC)	100000*	160 GB
Fusion-IO Device (MLC)	70 000*	320 GB
Intel SSD (SLC)	3500 writes / 35000 reads*	64 GB
Intel SSD (MLC)	8500 writes / 35000 reads*	160GB

来源 understanding the role of io bottleneck from Percona

对Oracle性能优化比较有用的部分常量.

事件名称	每次等待最大所需 容忍延时		此延时下每秒可处理 事件次数
单块磁盘读(物理读)	10 ms	0.010,000 s	100
从Oracle Buffer Cache中 的单块访问(逻辑读),500MHz CPU	20 μs	0.000,020 s	50,000
从Oracle Buffer Cache中 的单块访问(逻辑读),1G Hz CPU	10 μs	0.000,010 s	102,400
从Oracle Buffer Cache中 的单块访问(逻辑读),2G Hz CPU	5 μs	0.000 005 s	204,800
通过WAN传输SQL*Net消息	200 ms	0.200,000 s	5
通过LAN传输SQL*Net消息	15 ms	0.015,000 s	67
通过IPC传输SQL*Net消息	200 ms	0.001,000 s	1,000

此表来源 : useful Constants for the Oracle Performance Analyst

新看到部分IOPS以及延时的计算公式, 放在这儿, 可能对大家还有点用户.

RPM Rotations Per Minute	Rotations Per Second	Rotations Per Mili-second	Full Rotation	Rotational Latency (Half Rotation)	Average Seek Time	IO Time	IOPS
(x)	(x/60)	(x/60,000)	(1/ [x/60000] )	(1/ [x/60000] ) / 2
				Y	Z	(Y+Z)	(1/[Y+Z])*1000
15,000	15,000/60	15,000/ 60,000	4ms	2ms	4ms	6ms	167
10,000	10,000/60	10,000/ 60,000	6ms	3ms	5.15ms	8.15ms	122
			10ms	5ms	9ms	14ms	71
7,200	7200/60	7,200/ 60,000	8.4ms	4.2ms	9.9ms	14.1ms	71

摘自James Koopman 在 DBAsupport.com上的文章 Measuring Disk I/O―A Vendor View