Datacenter Workload Analysis & Qualification of SSD Storage … · 2021. 7. 20. · Windows Server...

2017 Storage Developer Conference. © Calypso Systems, Inc. All Rights Reserved.

Datacenter Workload Analysis &

Qualification of SSD Storage Servers

Eden KimCalypso Systems, Inc.


Datacenter Workloads & Storage Qualification

1. What are Datacenter Real World Storage Workloads?


3


An IO Stream1 is an Input/Output Operation (IO)

that has a unique:

1 Workload IO Stream definitions used here differ from SSD Endurance Streams where similar write operations are associated with a group of associated data

IO Stream Table: 2 Minute Capture Step showing IO Stream Statistics

• Random or Sequential Access

• Block Size or Data Transfer Size

A single IO Stream can occur many times during an IO Capture Step Other Secondary Metrics can be associated with IO Streams

• Read or Write IO

• Queue Depth (QD)


An IO Capture is the tabulation of statistics on IO

Streams that are observed during a capture period

• IO Capture Tools gather statistics and metrics on IO Streams

• An IO Capture is NOT an IO Trace

• No data or private information is collected

• Only binary numeric tables are gathered


IO Capture Tools are OS specific, vary by

the OS(s) supported, capture level and IO

Metrics taken• perfmon is a public tool for Windows

• blktrace is a public tool for Linux

• hiomon by hyperIO is for Windows

• IOProfiler at TestMyWorkload.com (by Calypso) is for Windows, MacOS, Linux & FreeBSD

TestMyWorkload.com is the official SNIA SSSI site for Reference IO Capturesoffering Free Capture tools, Analytics and Reference captures for public and SNIA Technical Works use2


RWSWs are key determinants in storage performance

and have a significant impact on SW and storage

optimizations• Solid State Storage Performance depends, in large part, on RWSWs

• Unlike lab test workloads, RWSWs are comprised of dynamically changing combinations of IO Streams & Demand Intensity

• IO Stream content affects Optimization, Design, Validation & Failure Analysis

• IO Streams change at each layer of software abstraction in the SW Stack


The Software (SW) Stack refers to the layers of

software (OS, APIs, programs, drivers and

abstractions) that exist between User space and

storage

Windows Software Stack

• IO Streams are generated in User space by software applications

• IO Streams traverse the SW Stack to storage and back

• IO Stream composition is different at different levels in the SW Stack


IO Streams are affected (modified) at each layer of Software abstraction.

Examples include:

• Software Applications & OS Kernel activities

• Metadata, Journaling, Caching, Packetization, Tiering

• IO Appending, Coalescing, Fragmentation, Merging

• Virtualization, Encryption, Deduplication, Compression

• Back-up, Cloning, Imaging, Snapshot, Replication

• Storage Architectures, Endurance Algorithms, SSD Optimizations

Meta-DataMerge Coalesce Append FragmentFile System Block IO VMs CloudWrites to cache Virtualization Encryption Data ReductionCompression De-Duplication Snapshot Back-up Clone

SANHyper Converge Scale Out Array LUN Physical NAS JBOF JBOD SSDSDS HBA


Solid State Storage Performance depends on how

well storage responds to constantly changing

combinations of IO Streams and Demand Intensity

RWSW – IOPS & Changing Combinations of IO Streams

RWSW - Throughput & Changing Queue Depths

• RWSWs are constantly changing combinations of IO Streams and QDs whereas Synthetic Lab tests are a fixed and constant workload

• IO Streams will have different Block Sizes, Accesses and Read or Write IOs

• Solid State Storage responds differently to the type of access (RND or SEQ), the Block Size, and whether the IO is a Read or a Write

• The type and combination of RWSW IO Streams and the Demand Intensity determines, in large part, the storage performance that is provided



2. Visualization of IO Capture Workloads


RWSW can be visualized by creating an IO

Stream Map that shows the changing

combinations of IOs and metrics over Time

IO Stream Map: 24-hour Block IO Level (Drive0) Capture showing IOPS & IO Streams

• IO Stream % probability of occurrence - different color data series

• IOPS - dominant black line

• Time - X-axis: 24-hour capture at 2 minute steps

• Secondary metrics captured by the Capture tool can be displayed


Secondary IO Metrics captured by the

IO Capture tool can be viewed on an IO

Stream Map

• IO Capture tools can capture various Secondary IO Metrics

• IO Streams can be listed by RND/SEQ access, Block Size & R/W IO

• Average & Maximum Response Times and QDs are shown to the left

• Additional IO Metrics can be shown for IO Count, Duplication Ratio, Compression Ratio, Disk Utilization, Reads, Writes and more


IO Streams can be filtered, extracted or presented

by specific Application IOs

• Here we extract only the sqlservr.exe IOs

• sqlservr.exe IOs that occur > 3% of the time over the the 24-hours

• The Cumulative workload - 395 Streams & 36 separate Processes

• sqlservr.exe – 6 IO Streams are 78% of the Total IO Streams

• sqlservr.exe application IOs - 79.9% of the Total IO Streams


RWSWs let us extract specific application

IOs to analyze the IO Composition, Metrics

and Performance that occur on the target

server during the IO Capture. We can see: IO Stream Composition of Selected Processes Changing Combinations of IO Streams

Application Process Response Times Throughput and Queue Depths v Time

• IO Stream Distribution of the selected Process(es)

• Changing combinations of IO Streams over time

• IO Process Average & Maximum Response Times

• IO Process Throughput and Average & Maximum Queue Depth

• Secondary IO Metrics gathered by the IO Capture tool



3. SNIA SSSI Reference IO Captures


Reference Workloads are Sample IO Captures posted to the

TestMyWorkload.com website

• Samples of recent user activity are posted for community viewing

• Used by SNIA Technical Work Groups for development of Technical Works

• Can be used as Benchmark Test Workloads for Datacenter Storage

• Can be used for general education & research

• 3 Reference IO Captures are currently posted


SNIA SSSI Reference IO Captures:

Example 3. 24-Hr Retail Web Portal Windows Server 2012R2Drive 0 & Drive 1 Block IO Level Captures

Example 4. SNIA Green Storage TWG WorkloadLinux OS - Block IO LevelIO capture of Synthetic Test Workload

Example 6. 24-Hr GPS Navigation PortalWindows Server 2012R2File System & Block IO Level



4. Selecting an IO Capture Workload for Analysis


6 Dominant IO Streams

over 24-Hour Capture

• RND 8K W 4.4%

• SEQ 64K R 5.6%

• SEQ 8K R 14.2%

• RND 8K R 16.4%

• SEQ 0.5K W 28.9%

• RND 64K R 30.5%


IO Streams can be used to analyze in-situ server performance as well as

used as a test workload to evaluate storage

• The 6 SQL IO Streams are used to analyze in-situ server performance

• ‘Self-Test’ presents IO Stream metrics (performance) from the capture

• The same SQL IO Streams can be used to test (and compare) storage

2017 Storage Developer Conference. © Calypso Systems, Inc. All Rights Reserved.29

Self-Test is the presentation of Server Performance

observed during the IO Capture event

• Also known as ‘In-Situ’ Server Performance Analysis

• Creates Performance Plots based on the host server activity

• Allows analysis and optimization of SW stack

• Provides a basis to create RWSW test stimuli


24-Hour sqlservr.exe workload

IOPS v Time

• IO Rate Throttled by Server Applications

• Relatively Low Disk Utilization

• Limited Demand Intensity

• HDD based storage


Periods of Differing Demand

Intensity (Queue Depths) and

Throughput

• 2 am Back-up Throughput (TP) Spike

• Low Queue Depths (QD) in Early Morning Hours

• High Queue Depths during Day time

• Varying Average QDs over 24-hour capture


Periods of Differing IO Stream

Combinations, Disk Utilization,

IOs and IOPS

• 2 am Back-up IOPS Spike

• Low Disk Utilization in Early Morning Hours

• High IOPS and Mixed IO Streams during Day time

• Varying IO Count over 24-hour capture


Periods of Differing Average

and Maximum Response

Times over 24-Hours

• Higher Response Times (RTs) with more Users (QD) / Disk Utilization

• Lower Response Times (RTs) with fewer Users (QD) / Disk Utilization

• Response Times reflect total server, application and storage activities



Average IOPS &

Average Response Time

• Limited IO Rates from server

• Periods of Low Disk Utilization

• Periods of Low Demand Intensity

• HDD based storage



Compression Ratio (CR) &

Duplication Ratios (DR)

• CR & DR analyzes data written to storage

• CR - measures how much MORE data can be compressed

• DR – measures how many written blocks are duplicated

• Compare File system and Block IO level to assess efficacy of Compression & Dedupe


The 24-Hour sqlservr.exe workload is used

to create two RWSW test workloads:

1. Composite 6 IO Streams – 6 IO Streams applied for every test step.

Used for Multi-WSAT, Individual Streams-WSAT & DIRTH tests. i.e.

each test step applies the same combination of 6 IO Streams.

2. 24-Hour Replay – reproduce each capture step combination of IO

Streams. Used for Replay-Native test. i.e. each test step reproduces

the unique combination of IO Streams that occurred in each of the

original IO Capture steps.


1. Multi-WSAT – applies fixed 6 IO Stream composite workload for each test step to Steady State.

2. Individual Streams-WSAT – tests each individual IO Stream as a separate Steady State measurement.

3. DIRTH (Demand Intensity Response time Histogram) - applies fixed 6 IO Stream composite workload across a range of 1 to 1,024 Users to measure IOPS & Response Time saturation.

4. Replay-Native - reproduces each capture step combination of IO Streams, Queue Depths and Idle Times for storage comparison to the original IO Capture server storage

Multi-WSAT Individual Streams-WSAT

DIRTH Replay-Native


The fixed Composite 6 IO

Stream workload is applied to

Steady State

• Samsung SSD has highest performance followed by Seagate and Micron SSDs

• Sandisk SSD and Seagate SAS HDD are lower

• See component IO Stream performance in the following Individual Streams-WSAT results


Each component IO Stream is

applied to Steady State

• Samsung SSD has highest overall performance

• Sandisk SSD has highest RND 8K R

• Micron SSD has highest RND 8K W

• Note the SEQ 0.5K W performance differential

• SEQ 0.5K W are 28.9% of the total workload and explains the difference in overall performance


The Fixed IO Stream composite

workload is applied across a

range of 1 to 1,024 Users


• Host Server QD Range is Ave QD 5, Max QD 306

• Test Performance at 32 Users is highlighted (red box)

• Note that Ordinal Rank is consistent across Users

Host QD Range


Reproduces the IO Capture

step IO Stream combinations,

QDs and Idle times for 24-Hrs


• Seagate SSD is second highest

• Micron SSD is close to the group mean

• Sandisk SSD and Seagate SSD are lower

• Note Self-Test reference baseline (red dotted line)



6. Conclusions


• Understanding Your RWSW is critical for Datacenter, Storage Server and SSD Design and Optimization

• Know what you are optimizing (IO Streams & SW Stack levels)

• Find out what IO Streams are presented to Storage

• Try Demos, Free Captures & Analysis at TestMyWorkload.com

• See SNIA Reference Captures at TestMyWorkload.com

• Download the White Paper at TestMyWorkload.com for full data analysis of the presented tests and sample pool drives

• www.TestMyWorkload.com

http://www.testmyworkload.com/


www.TestMyWorkload.com

http://www.testmyworkload.com/

Datacenter Workload Analysis & Qualification of SSD Storage … · 2021. 7. 20. · Windows Server...

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