Disk Array Performance Estimation

AGH University of Science and TechnologyDepartment of Computer Science

Jacek Marmuszewski

Darin Nikołow, Marek Pogoda, Renata Slota, Jacek Kitowski

Outline Introduction

motivation for performance estimation of disk array

problems connected with estimation of disk array

requirements for disk array estimator

Solution

Environment

Disk Array Performance Tests

Estimation Model

Estimation Quality Tests

Future work

Introductionmotivation for performance estimation of disk array

Proper and efficient performance estimation of storage systems is essential for many processes occurring in distributed computational environments such as:

replica selection,

new replica creation,

creating VO specifying data storage performance

requirements in SLA,

guarantying the fulfillment of SLA within VO.

Introductionproblems connected with estimation of disk array

Complexity of algorithms used to determine best solution for storing data

Shared resources

Virtualization

Introductionrequirements for disk array estimator

Estimator response time Estimator response time Estimation quality

Solution

Model identification via active experiments

Environmentgeneral view

- Disk Array - Host / Server - User / Application

Test Environment

Disk Array 1

Infortrend A16F-G2430

2GB cache

16x 1TB HDD – SATA, RAID6

2x 4/8 Gbit/s fiber channel interface

Server 1

Xeon QuadCore

4GB RAM

Disk Array 2

Intel Entery Storage System SS4200-E

4 x 500GB HDD - SATA

RAID5

1 Gbit Ethernet

Server 2

Intel Core2Duo E4400 2.0Ghz

2GB RAM

Test Environment

- Disk Array - Host / Server

Monitoring daemon

Monitoring daemon

Monitoring daemon

Estimator Service & database

Sending data using ICE

ICE – Internet Communication Engine form ZeroC

Disk Array Performance Tests

Tests written in C

Using 'fwrite'

Synchronizing (flushing) once – before ending test

usu

Disk Array Performance Tests

Disk Array Performance Tests

Model

How to obtain those values automatically ?

Model

size

speed

- stored in cache

- stored on HDDs

Cache size

Model

Cache usage estimation

Monitoring i/o operation on every host!

Knowledge of NIC speed and HDDs speed

Best way : Get this information directly form Disk Array

Model

Multiple users – average bandwidth usage

Divide bandwidth equally to all hosts

On host, divide bandwidth equally to all users

If host/user in not using its all bandwidth divide it to others

Use this value as „Max Disk Array Speed”

Do the same for „Max HDD's speed” value

Model

Multiple users – estimating future r/w speed

Don't use current speed!

Use weighted mean for statistical r/w data.

History time History time

speedspeed

time time

s0 s1 s2 s3 s0 s1 s2 s3

AvgSpeed=1*s0 + 2*s1 + 4*s2 + 8*s3

15 AvgSpeed=∑i=0

2 i∗si

∑i=0

2 i

Estimation quality tests

Estimation quality tests

Estimation quality testsfor multiple users

Estimation quality testsfor multiple users

Estimation quality testsfor multiple users

Average absolute performance estimation error: 34,8 MB/s

Maximal absolute performance estimation error: 64,4 MB/s

Average absolute performance estimation error: 8,2 %

Maximal absolute performance estimation error: 13,9 %

Average estimator response time (+ ICE) = ~1.2ms

ICE – Internet Communication Engine form ZeroC

Summary and Future Works

Collecting more data directly form Disk Array administration / diagnostic tools

Analyzing more data – searching for patterns in Disk Array usage.

Thank You