Shulou(Shulou.com)06/02 Report--

II. IOPS Description

2.1 IOPS (Input/OutputPer Second)

IOPS, or the number of inputs and outputs (or reads and writes) per second, is one of the primary metrics for measuring disk performance.

IOPS refers to the number of I/O requests that the system can handle per unit of time, usually in the number of I/O requests processed per second. I/O requests are usually read or write data operation requests. Random read and write frequent applications,

For example, OLTP(Online Transaction Processing), IOPS is a key metric.

Another important metric is data throughput, which refers to the amount of data that can be successfully transmitted per unit time. For applications with a large number of sequential reads and writes, such as VOD(Video On Demand), more attention is paid to throughput metrics.

Traditional disks are essentially mechanical devices, such as FC, SAS, SATA disks, which typically run at speeds ranging from 5400/7200/10K/15K rpm. The key factor affecting disk is disk service time, that is, the time it takes for disk to complete an I/O request, which consists of seek time, rotation delay and data transfer time.

(1) Seek time

Tseek is the time required to move the read/write head to the correct track. The shorter the seek time, the faster the I/O operation, and the average seek time for disks is currently 3-15 ms.

(2) Rotation delay

Trotation is the time required for disk rotation to move the sector where the requested data is located beneath the read/write head. The spin delay depends on the disk speed and is usually expressed as 1/2 of the time required for a disk revolution.

For example, the average spin latency of a disk at 7200 rpm is approximately 60*1000/7200/2 = 4.17 ms, while the average spin latency of a disk at 15000 rpm is approximately 2 ms.

(3) Data transmission time

Ttransfer refers to the time required to complete the transmission of the requested data, which depends on the data transfer rate and has a value equal to the data size divided by the data transfer rate.

Currently IDE/ATA can reach 133MB/s (MBPS), SATA II can reach 300MB/s interface data transfer rate, data transfer time is usually much less than the first two parts of the time.

IOPS = 1s/(seek time + rotational latency + data transfer time)

Therefore, it is theoretically possible to calculate the maximum IOPS of the disk, i.e. IOPS = 1000ms/ (Tseek + Troation), ignoring the data transfer time. Assuming an average physical seek time of 3ms and disk speeds of 7200,10K, and 15Krpm, the theoretical maximum disk IOPS are:

IOPS = 1000 / (3 + 60000/7200/2) = 140

IOPS = 1000 / (3 + 60000/10000/2) = 167

IOPS = 1000 / (3 + 60000/15000/2) = 200

2.2 IOPS of SSD

SSD is an electronic device that avoids the time spent on seek and rotation of traditional disks, and the addressing overhead of storage units is greatly reduced, so IOPS can be very high, reaching tens or even hundreds of thousands.

In actual measurements, IOPS numbers are affected by many factors, including I/O load characteristics (read/write ratio, sequential versus random, number of worker threads, queue depth, data record size), system configuration, operating system, disk drives, and more.

Therefore, when comparing disk IOPS measurements, they must be performed against the same test benchmark, even if there is some random uncertainty.

Typically, IOPS can be broken down into the following metrics:

Toatal IOPS: Disk IOPS under mixed read and write and sequential random I/O load, which is most consistent with actual I/O, and most applications focus on this metric.

Random Read IOPS: IOPS with 100% random read load.

Random WriteIOPS: IOPS with 100% random write load.

Sequential Readout IOPS: IOPS with 100% sequential load read.

Sequential WriteIOPS: IOPS with 100% sequential write load.

III.ORION Tool Description

ORION (Oracle I/O Calibration Tool) is an independent tool introduced by Oracle to calibrate the I/O performance of a database storage system. For a description of the tool, refer to:

Oracle ORION IO Test Tool

http://blog.csdn.net/tianlesoftware/article/details/5965331

Let's test it with ORION tools to see:

[root@qs-xe-dzora-pd software]# cat dave.lun

/dev/sdb1

[root@qs-xe-dzora-pd software]# ./ orion_linux_x86-64 -run advanced -testname dave -num_disks 2

ORION: ORacle IO Numbers -- Version11.1.0.7.0

dave_20111026_2026

Test will take approximately 16 minutes

Larger caches may take longer

View the results generated:

[root@qs-xe-dzora-pd software]# ls dave*

dave_20111026_2026_iops.csv dave_20111026_2026_summary.txt dave.lun_20111026_2025_summary.txt

dave_20111026_2026_lat.csv dave_20111026_2026_trace.txt

dave_20111026_2026_mbps.csv dave.lun

[root@qs-xe-dzora-pd software]# cat dave_20111026_2026_summary.txt

ORION VERSION 11.1.0.7.0

Commandline:

-run advanced -testname dave -num_disks 2

This maps to this test:

Test: dave

Small IO size: 8 KB

Large IO size: 1024 KB

IO Types: Small Random IOs, Large RandomIOs

Simulated Array Type: CONCAT

Write: 0%

Cache Size: Not Entered

Duration for each Data Point: 60 seconds

Small Columns:, 0

Large Columns:, 0, 1, 2, 3, 4

Total Data Points: 15

Name: /dev/sdb1 Size: 449495069184

1 FILEs found.

Maximum Large MBPS=159.61 @ Small=0 andLarge=4 #

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