IOPs and Capacity Planning Guidelines for Indexing

Table of Contents

Overview

Index Cache Directory Recommendation

Iometer On Windows

Iometer On Linux

Overview

This document describes how to plan for and measure Input Output Operations per second (IOPs) when assigning space for Index Cache.

The following section explains the use of Iometer which is a widely used industry standard tool for measuring IOPs. Using IOPs rating provides a standard and simplified way to commission storage without having to understand and use proprietary tools.

Index Cache Directory Recommendation

After configuring Index cache Directory space, run Iometer to confirm the volumes provide recommended IOPs as described in the below table.

IoMeter On Windows

1. Installing Iometer

   Download and install Iometer on the MediaAgent where index cache directory need to be tested.

   Iometer can be downloaded from www.iometer.org.

2. Running Iometer with Single Worker Thread

   Worker thread is an entity that runs the test defined under Access Specification Tab of IoMeter UI. Multiple worker threads run the tests in parallel to test concurrent performance.

   Use the following steps to run Iometer using single worker thread:

   1. Right-click Iometer and click Run as Administrator.

      

   2. The Iometer dialog box will appear.
   3. Click on the name of the computer available in the Topology panel on the left side of the window.

      The available disk drives will appear in the Disk Targets tab.

      IoMeter, on startup, creates one Manager with multiple worker threads. Leave one worker thread and delete remaining worker threads by selecting the worker thread and clicking the Disconnect Selected Worker or Manager button.

      It is recommended to run Iometer on the physical disk that represents the storage volume for which IOPs need to be measured. Iometer will allow physical disks to be selected only when there are no volumes on the disk. If IoMeter needs to be run on the volume, it is recommended that the volume have at least 60% free space. For example, if a volume is 500 GB in size, a minimum of 300 GB should be free.

      

   4. In the Disk Targets tab, select a disk to use in the test.

      Values for Maximum Disk Size and Starting Disk Sector should be set to default, that is 0, to test the complete disk.

      If running the test on a volume, Iometer needs to prepare the volume. It creates a file named iobw.tst file as part of this preparation phase and runs read/write tests on this file.

      In the figure, blue disk icon represents a physical drive which has no partitions on them. Yellow disk icons with a red strike through are the volumes need to be prepared before the test. This are the volumes that do not contain iobw.tst file. Yellow disk without the strike through contain iobw.tst file. Example of prepared volume is G: whereas other volumes are un-prepared.

      In the following figure, PHYSICALDRIVE:2 is the disk selected for the test.

      

3. Access Specifications

   1. Click the Access Specifications tab.
   2. From the Global Access Specifications area, select the IoMeter profile that needs to be used for IOPs measurement test.

      

      Recommended Iometer Profile for Testing Index Cache Directory

      4K Block Size, 100% Access, 100% Random, 50% Read and 50% Write

      This profile closely emulates the way in which disk is accessed by C-tree database lookups.

      

4. Results Display

   Click the Results Display tab.

   Change Update Frequency slider to 5 seconds.

   

5. Test Setup

   Click the Test Setup tab.

   Set the time Run Time to 30 minutes

   

6. Results

   1. Press the Start Tests button (green flag) to run IOMeter test.
   2. A standard Save File dialog will appears. Select a file to store the test results (by default it saves as results.csv)

      After a few seconds the test results will appear in the Results Display tab.

      Run the test for around 30 minutes or until IOPs value stabilized.

   3. Press the Stop Test button (stop sign). The test stops and the final results are saved in the results.csv file. This can be viewed in any text editor.

      At the end of the test, note down the IOPs test rating. In the below figure, IOPs rating for the volume under test is 329.31 with one worker thread.

   4. If you are running IoMeter on a volume, make sure to delete iobw.tst file after the test is complete.

      

Run Iometer With Multiple Worker Thread

Use the following steps to run Iometer with 8 worker thread:

1. Follow the steps described in the below sections to run Iometer with single worker thread and set the access specifications.
   1. Installing Iometer
   2. Running Iometer
   3. Access Specifications
2. Click the Start a Duplicate of This Worker on This Manager button to create a duplicate worker thread with the same settings.

   Create a total of 8 worker thread.

3. Run the test by following the steps described in below sections:
   1. Results Display
   2. Test Setup
   3. Results

   

Iometer On Linux

To test the disk available on linux machine, Iometer requires two components, Iometer UI and Dynamo. The Iometer UI is run on Windows host. It is possible to load the Dynamo workload generator on another host (linux host). In the following case, the Linux host running Dynamo is the machine under test, and the Windows host running the Iometer UI is just reporting the numbers.

1. To perform Iometer test on linux machine two hosts are required:

   Windows host that runs Iometer UI

   The Linux MediaAgent that runs dynamo to test the disks.

   For installation instructions, refer to Iometer documentation on Iometer website.

2. After installation, verify network connectivity between the two machines, make sure both the machine can ping each other. Run dynamo on linux MediaAgent with two parameters:

   -i -- Indicates the IP address of Windows host running Iometer UI

   -m -- Indicates the IP address of Linux host

   In the figure below, 100.10.100.12 IP address specified by –I parameter is the IP address of Windows host and IP address 100.10.100.23 specified by –m is that of linux host.

   
3. After running dynamo, run Iometer with administrator privileges on Windows host. See the following sections:
   • Running Iometer with Single Worker Thread - to run IoMeter test using single worker thread
   • Run Iometer With Multiple Worker Thread - to run IoMeter test using eight worker thread

   Iometer needs to be run after running dynamo on the Linux host..

   In this figure, under All Managers, FARGO is the Windows host and flystone69 is the Linux MediaAgent.