SlideShare a Scribd company logo
Apache HBase at DiDi
Kang Yuan
Agenda
1. About Us
2. DiDi HBase Platform
3. Application and Solution
4. Challenges and future
About Us
• DiDi
• In <Silicon valley>
About Us
• DiDi
• the world’s leading mobile transportation platform
• 20 million rides on a daily basis
Express Mini Bus Bus
Luxury Car Car pool Taxi
Premier Designated
driver
Trial run
Rental Car Taxi For
Aged
ofo sharing
Bike
About Us
• Mission
To Redefine the Future of Mobility
• Vision
To become a global leader in smart transportation and automotive
technology, the world’s largest operator of vehicle networks and a global
leader in smart transportation systems
About Us
• HBase Team:4 Developers
• Kang Yuan
• Yang Li
• Hanzhi Zhang
• Jingyi Yao
• Attached to BigData Architecture Department
• Cooperate with Hadoop/Hive/Spark/Flink/Druid Team closely
DiDi HBase Platform
• Cluster(3)
• Storage Cluster – location A
• Compute Cluster – location B
• Storage Cluster – location B
• Location A: the same place with the hadoop Cluster
• Location B: for online business or streaming
• Application(50+ business and 160+ tables)
• Batching Job result storage
• Online writing/reading
• Persistence for Streaming Jobs
• 99.95% available
DiDi HBase Platform
• HBase Version
• Based on 0.98.21
• Region Group patch HBASE-6721
• Thrift2 patch
• Multi-tenant Problem
• A bad table can put down a cluster
• We don’t know who the tables belong to
DiDi HBase Platform
• Region Group
DiDi HBase Platform
• Region Group
• Isolate important use cases from others
• Easy to manage(web ui, user group, operation tools)
• Elastic to assign resources
• Different Configuration in one Cluster(for different machine types,
business, testing etc)
• Easy to compute the cost of the business
• Easy to upgrade the regionserver in one Group before do it in the whole
cluster
• Cost(share pool) = TableSize*x x = cost/GB
• Cost(specific group ) = Rscount*y y = cost/RS
DiDi HBase Platform
• Improvement
• Web UI to show group
• MoveTables bug fix
• CreateTableHandler fix
DiDi HBase Platform
DiDi HBase Platform
• DiDi HBase Service
DiDi HBase Platform
Create Project and Tables
DiDi HBase Platform
workflow
DiDi HBase Platform
Monitor your tables
Get your bill, user must care for their cost
DiDi HBase Platform
• Phoenix
• Advantage
• Easy to use for RDBMS User(jdbc、sql)
• Auto salting table for performance and hot spot avoiding
• Like a Big Mysql(One sentence to explain to our users)
• Disadvantage
• Some bug like ordering vector item
• Unstable statistic info caching
• No good in Join case
• So many other hotter system :Presto/Impala/Spark SQL/Kylin
• Successful Use
• Row Timestamp
• Multidimensional Table Schema
• Phoenix(more customers recently)
• Row Timestamp for metrics
• Monitoring table write/read/storage
• Easy to compute avg, max, min for metrics
• Quick to query recently data
• Multi-dimension Table Schema
• MR/Spark Job to compute BI reporting data
• Many demission combination result like city, gender, age, business type
• Primary Key: JobID, date, dimission1, dimission2, dimission3…
• Value: dimNameArray, valueArray
• This can fit nearly all the Multi-dimension reporting business
DiDi HBase Platform
DiDi HBase Platform
• Client Access
• Multiple Languages Clients
• C++, Go, Python, PHP
• Thritf2, QueryServer
• Security(ACL)
Application and Solution(Hadoop Monitor)
• Hadoop Monitor
• Help hadoop to query their fsimage and jobhistory
• BI for Hadoop manager
• Store data in phoenix
Application and Solution
Application and Solution(Gis Query)
• GPS
Application and Solution
• GPS
• Query Model
• Rowkey:ID+Timestamp
• Rowkey:Reversed GeoHash+timestamp+ID
• GeoHash
• A index in two dimensions
• Fit HBase rowkey prefect
• Point 1: same prefix code result in a nearby place
• Point 2: query rowkey prefix can location a region whose area decided by
prefix length
Application and Solution
• GPS
• GeoHash
Application and Solution(Online Machine Learning)
• ETA(Estimated Time of Arrival)
• Origin data collection
• ETL
• Feature extraction
• Storage
• Model Training
Application and Solution
• ETA(Estimated Time of Arrival)
• Training data by spark, every 30 minutes
• Pick up data by city from HBase in 5 minutes
• Compute ETA in 25 minutes
• Rowkey: Salting+CityId+Type0+Type1+Type2+Timestamp
• Columns: Order,Feature
• Every day HBase data will be dumped into HDFS for offline training
Application and Solution(Image)
• Traffic in Cloud
• High Volume Throughput, Little Read
• Read via 8 Thrift nodes
• Road traffic info
• POI data
• Heat-map
• Write with Spark Job
Application and Solution
• Architecture
Challenges and future
• More connect with other bigdata framework
• Hive Phoenix/HBase Handler
• Integration with hive
• Use Hive sql to query phoenix
• Easy to load data from hadoop cluster
• Join with Hive table
• Spark Phoenix/HBase Handler
Challenges and future
• More stable
• hbase1.x upgrade
• OLAP extends
• Kylin
• TPC-H Compare
• Thrift load balancer
• Auto Group balancer
• More powerful DHS
Any Question?

More Related Content

What's hot (20)

PDF
HBaseConAsia2018 Track3-6: HBase at Meituan
Michael Stack
 
PPTX
HBaseCon 2012 | Building a Large Search Platform on a Shoestring Budget
Cloudera, Inc.
 
PPTX
HBaseConAsia2018 Track2-4: HTAP DB-System: AsparaDB HBase, Phoenix, and Spark
Michael Stack
 
PPTX
HBaseConAsia2018 Track2-3: Bringing MySQL Compatibility to HBase using Databa...
Michael Stack
 
PDF
HBaseConAsia2018 Track3-3: HBase at China Life Insurance
Michael Stack
 
PDF
hbaseconasia2017: HBase Disaster Recovery Solution at Huawei
HBaseCon
 
PPTX
HBaseConAsia2018 Track1-5: Improving HBase reliability at PInterest with geo ...
Michael Stack
 
PDF
HBaseConAsia2018 Track1-1: Use CCSMap to improve HBase YGC time
Michael Stack
 
PPT
HBaseCon 2012 | You’ve got HBase! How AOL Mail Handles Big Data
Cloudera, Inc.
 
PPTX
HBaseConAsia2018 Track3-7: The application of HBase in New Energy Vehicle Mon...
Michael Stack
 
PPTX
HBase at Bloomberg: High Availability Needs for the Financial Industry
HBaseCon
 
PDF
HBaseCon 2015- HBase @ Flipboard
Matthew Blair
 
PDF
HBaseConAsia2018 Keynote1: Apache HBase Project Status
Michael Stack
 
PPTX
Transform your DBMS to drive engagement innovation with Big Data
Ashnikbiz
 
PDF
25 snowflake
剑飞 陈
 
PPTX
HBaseCon 2015 General Session: Zen - A Graph Data Model on HBase
HBaseCon
 
PDF
CosmosDB for DBAs & Developers
Niko Neugebauer
 
PPTX
HBaseConAsia2018 Track3-5: HBase Practice at Lianjia
Michael Stack
 
PPTX
RedisConf17 - Home Depot - Turbo charging existing applications with Redis
Redis Labs
 
PPTX
HBaseCon 2015: Optimizing HBase for the Cloud in Microsoft Azure HDInsight
HBaseCon
 
HBaseConAsia2018 Track3-6: HBase at Meituan
Michael Stack
 
HBaseCon 2012 | Building a Large Search Platform on a Shoestring Budget
Cloudera, Inc.
 
HBaseConAsia2018 Track2-4: HTAP DB-System: AsparaDB HBase, Phoenix, and Spark
Michael Stack
 
HBaseConAsia2018 Track2-3: Bringing MySQL Compatibility to HBase using Databa...
Michael Stack
 
HBaseConAsia2018 Track3-3: HBase at China Life Insurance
Michael Stack
 
hbaseconasia2017: HBase Disaster Recovery Solution at Huawei
HBaseCon
 
HBaseConAsia2018 Track1-5: Improving HBase reliability at PInterest with geo ...
Michael Stack
 
HBaseConAsia2018 Track1-1: Use CCSMap to improve HBase YGC time
Michael Stack
 
HBaseCon 2012 | You’ve got HBase! How AOL Mail Handles Big Data
Cloudera, Inc.
 
HBaseConAsia2018 Track3-7: The application of HBase in New Energy Vehicle Mon...
Michael Stack
 
HBase at Bloomberg: High Availability Needs for the Financial Industry
HBaseCon
 
HBaseCon 2015- HBase @ Flipboard
Matthew Blair
 
HBaseConAsia2018 Keynote1: Apache HBase Project Status
Michael Stack
 
Transform your DBMS to drive engagement innovation with Big Data
Ashnikbiz
 
25 snowflake
剑飞 陈
 
HBaseCon 2015 General Session: Zen - A Graph Data Model on HBase
HBaseCon
 
CosmosDB for DBAs & Developers
Niko Neugebauer
 
HBaseConAsia2018 Track3-5: HBase Practice at Lianjia
Michael Stack
 
RedisConf17 - Home Depot - Turbo charging existing applications with Redis
Redis Labs
 
HBaseCon 2015: Optimizing HBase for the Cloud in Microsoft Azure HDInsight
HBaseCon
 

Similar to HBaseCon2017 Apache HBase at Didi (20)

PPTX
Introduction to Apache HBase
Gokuldas Pillai
 
PDF
Intro to HBase - Lars George
JAX London
 
PPTX
Big Data on azure
David Giard
 
ODP
HBase introduction talk
Hayden Marchant
 
PDF
Nyc hadoop meetup introduction to h base
智杰 付
 
PPTX
Hbasepreso 111116185419-phpapp02
Gokuldas Pillai
 
PDF
Architectural Evolution Starting from Hadoop
SpagoWorld
 
PPTX
Unit II Hadoop Ecosystem_Updated.pptx
BhavanaHotchandani
 
PDF
Hadoop Infrastructure (Oct. 3rd, 2012)
John Dougherty
 
PDF
Mar 2012 HUG: Hive with HBase
Yahoo Developer Network
 
PDF
Hbase: an introduction
Jean-Baptiste Poullet
 
PDF
Big data and mstr bridge the elephant
Kognitio
 
PPT
Chicago Data Summit: Apache HBase: An Introduction
Cloudera, Inc.
 
PPTX
Big data solutions in Azure
Mostafa
 
PDF
Big Data Solutions in Azure - David Giard
ITCamp
 
PDF
Hbase jdd
Andrzej Grzesik
 
PPTX
מיכאל
sqlserver.co.il
 
KEY
HBase and Hadoop at Urban Airship
dave_revell
 
PDF
Michael stack -the state of apache h base
hdhappy001
 
ODP
Hadoop demo ppt
Phil Young
 
Introduction to Apache HBase
Gokuldas Pillai
 
Intro to HBase - Lars George
JAX London
 
Big Data on azure
David Giard
 
HBase introduction talk
Hayden Marchant
 
Nyc hadoop meetup introduction to h base
智杰 付
 
Hbasepreso 111116185419-phpapp02
Gokuldas Pillai
 
Architectural Evolution Starting from Hadoop
SpagoWorld
 
Unit II Hadoop Ecosystem_Updated.pptx
BhavanaHotchandani
 
Hadoop Infrastructure (Oct. 3rd, 2012)
John Dougherty
 
Mar 2012 HUG: Hive with HBase
Yahoo Developer Network
 
Hbase: an introduction
Jean-Baptiste Poullet
 
Big data and mstr bridge the elephant
Kognitio
 
Chicago Data Summit: Apache HBase: An Introduction
Cloudera, Inc.
 
Big data solutions in Azure
Mostafa
 
Big Data Solutions in Azure - David Giard
ITCamp
 
Hbase jdd
Andrzej Grzesik
 
מיכאל
sqlserver.co.il
 
HBase and Hadoop at Urban Airship
dave_revell
 
Michael stack -the state of apache h base
hdhappy001
 
Hadoop demo ppt
Phil Young
 
Ad

More from HBaseCon (20)

PDF
hbaseconasia2017: Building online HBase cluster of Zhihu based on Kubernetes
HBaseCon
 
PDF
hbaseconasia2017: HBase on Beam
HBaseCon
 
PDF
hbaseconasia2017: Removable singularity: a story of HBase upgrade in Pinterest
HBaseCon
 
PDF
hbaseconasia2017: Apache HBase at Netease
HBaseCon
 
PDF
hbaseconasia2017: HBase在Hulu的使用和实践
HBaseCon
 
PDF
hbaseconasia2017: 基于HBase的企业级大数据平台
HBaseCon
 
PDF
hbaseconasia2017: HBase at JD.com
HBaseCon
 
PDF
hbaseconasia2017: Large scale data near-line loading method and architecture
HBaseCon
 
PDF
hbaseconasia2017: Ecosystems with HBase and CloudTable service at Huawei
HBaseCon
 
PDF
hbaseconasia2017: HBase Practice At XiaoMi
HBaseCon
 
PDF
hbaseconasia2017: hbase-2.0.0
HBaseCon
 
PDF
HBaseCon2017 Democratizing HBase
HBaseCon
 
PDF
HBaseCon2017 Removable singularity: a story of HBase upgrade in Pinterest
HBaseCon
 
PDF
HBaseCon2017 Quanta: Quora's hierarchical counting system on HBase
HBaseCon
 
PDF
HBaseCon2017 Transactions in HBase
HBaseCon
 
PDF
HBaseCon2017 Highly-Available HBase
HBaseCon
 
PDF
HBaseCon2017 gohbase: Pure Go HBase Client
HBaseCon
 
PDF
HBaseCon2017 Improving HBase availability in a multi tenant environment
HBaseCon
 
PDF
HBaseCon2017 Spark HBase Connector: Feature Rich and Efficient Access to HBas...
HBaseCon
 
PDF
HBaseCon2017 HBase at Xiaomi
HBaseCon
 
hbaseconasia2017: Building online HBase cluster of Zhihu based on Kubernetes
HBaseCon
 
hbaseconasia2017: HBase on Beam
HBaseCon
 
hbaseconasia2017: Removable singularity: a story of HBase upgrade in Pinterest
HBaseCon
 
hbaseconasia2017: Apache HBase at Netease
HBaseCon
 
hbaseconasia2017: HBase在Hulu的使用和实践
HBaseCon
 
hbaseconasia2017: 基于HBase的企业级大数据平台
HBaseCon
 
hbaseconasia2017: HBase at JD.com
HBaseCon
 
hbaseconasia2017: Large scale data near-line loading method and architecture
HBaseCon
 
hbaseconasia2017: Ecosystems with HBase and CloudTable service at Huawei
HBaseCon
 
hbaseconasia2017: HBase Practice At XiaoMi
HBaseCon
 
hbaseconasia2017: hbase-2.0.0
HBaseCon
 
HBaseCon2017 Democratizing HBase
HBaseCon
 
HBaseCon2017 Removable singularity: a story of HBase upgrade in Pinterest
HBaseCon
 
HBaseCon2017 Quanta: Quora's hierarchical counting system on HBase
HBaseCon
 
HBaseCon2017 Transactions in HBase
HBaseCon
 
HBaseCon2017 Highly-Available HBase
HBaseCon
 
HBaseCon2017 gohbase: Pure Go HBase Client
HBaseCon
 
HBaseCon2017 Improving HBase availability in a multi tenant environment
HBaseCon
 
HBaseCon2017 Spark HBase Connector: Feature Rich and Efficient Access to HBas...
HBaseCon
 
HBaseCon2017 HBase at Xiaomi
HBaseCon
 
Ad

Recently uploaded (20)

DOCX
Cryptography Quiz: test your knowledge of this important security concept.
Rajni Bhardwaj Grover
 
DOCX
Python coding for beginners !! Start now!#
Rajni Bhardwaj Grover
 
PDF
Future-Proof or Fall Behind? 10 Tech Trends You Can’t Afford to Ignore in 2025
DIGITALCONFEX
 
PPTX
From Sci-Fi to Reality: Exploring AI Evolution
Svetlana Meissner
 
PPTX
Mastering ODC + Okta Configuration - Chennai OSUG
HathiMaryA
 
PPT
Ericsson LTE presentation SEMINAR 2010.ppt
npat3
 
PDF
NLJUG Speaker academy 2025 - first session
Bert Jan Schrijver
 
PDF
Reverse Engineering of Security Products: Developing an Advanced Microsoft De...
nwbxhhcyjv
 
PDF
“NPU IP Hardware Shaped Through Software and Use-case Analysis,” a Presentati...
Edge AI and Vision Alliance
 
PDF
Newgen 2022-Forrester Newgen TEI_13 05 2022-The-Total-Economic-Impact-Newgen-...
darshakparmar
 
PDF
AI Agents in the Cloud: The Rise of Agentic Cloud Architecture
Lilly Gracia
 
PPTX
AI Penetration Testing Essentials: A Cybersecurity Guide for 2025
defencerabbit Team
 
PPTX
Future Tech Innovations 2025 – A TechLists Insight
TechLists
 
PDF
Staying Human in a Machine- Accelerated World
Catalin Jora
 
PDF
The 2025 InfraRed Report - Redpoint Ventures
Razin Mustafiz
 
PPTX
The Project Compass - GDG on Campus MSIT
dscmsitkol
 
PDF
Kit-Works Team Study_20250627_한달만에만든사내서비스키링(양다윗).pdf
Wonjun Hwang
 
PDF
Mastering Financial Management in Direct Selling
Epixel MLM Software
 
PPTX
COMPARISON OF RASTER ANALYSIS TOOLS OF QGIS AND ARCGIS
Sharanya Sarkar
 
PDF
Transcript: Book industry state of the nation 2025 - Tech Forum 2025
BookNet Canada
 
Cryptography Quiz: test your knowledge of this important security concept.
Rajni Bhardwaj Grover
 
Python coding for beginners !! Start now!#
Rajni Bhardwaj Grover
 
Future-Proof or Fall Behind? 10 Tech Trends You Can’t Afford to Ignore in 2025
DIGITALCONFEX
 
From Sci-Fi to Reality: Exploring AI Evolution
Svetlana Meissner
 
Mastering ODC + Okta Configuration - Chennai OSUG
HathiMaryA
 
Ericsson LTE presentation SEMINAR 2010.ppt
npat3
 
NLJUG Speaker academy 2025 - first session
Bert Jan Schrijver
 
Reverse Engineering of Security Products: Developing an Advanced Microsoft De...
nwbxhhcyjv
 
“NPU IP Hardware Shaped Through Software and Use-case Analysis,” a Presentati...
Edge AI and Vision Alliance
 
Newgen 2022-Forrester Newgen TEI_13 05 2022-The-Total-Economic-Impact-Newgen-...
darshakparmar
 
AI Agents in the Cloud: The Rise of Agentic Cloud Architecture
Lilly Gracia
 
AI Penetration Testing Essentials: A Cybersecurity Guide for 2025
defencerabbit Team
 
Future Tech Innovations 2025 – A TechLists Insight
TechLists
 
Staying Human in a Machine- Accelerated World
Catalin Jora
 
The 2025 InfraRed Report - Redpoint Ventures
Razin Mustafiz
 
The Project Compass - GDG on Campus MSIT
dscmsitkol
 
Kit-Works Team Study_20250627_한달만에만든사내서비스키링(양다윗).pdf
Wonjun Hwang
 
Mastering Financial Management in Direct Selling
Epixel MLM Software
 
COMPARISON OF RASTER ANALYSIS TOOLS OF QGIS AND ARCGIS
Sharanya Sarkar
 
Transcript: Book industry state of the nation 2025 - Tech Forum 2025
BookNet Canada
 

HBaseCon2017 Apache HBase at Didi

  • 1. Apache HBase at DiDi Kang Yuan
  • 2. Agenda 1. About Us 2. DiDi HBase Platform 3. Application and Solution 4. Challenges and future
  • 3. About Us • DiDi • In <Silicon valley>
  • 4. About Us • DiDi • the world’s leading mobile transportation platform • 20 million rides on a daily basis Express Mini Bus Bus Luxury Car Car pool Taxi Premier Designated driver Trial run Rental Car Taxi For Aged ofo sharing Bike
  • 5. About Us • Mission To Redefine the Future of Mobility • Vision To become a global leader in smart transportation and automotive technology, the world’s largest operator of vehicle networks and a global leader in smart transportation systems
  • 6. About Us • HBase Team:4 Developers • Kang Yuan • Yang Li • Hanzhi Zhang • Jingyi Yao • Attached to BigData Architecture Department • Cooperate with Hadoop/Hive/Spark/Flink/Druid Team closely
  • 7. DiDi HBase Platform • Cluster(3) • Storage Cluster – location A • Compute Cluster – location B • Storage Cluster – location B • Location A: the same place with the hadoop Cluster • Location B: for online business or streaming • Application(50+ business and 160+ tables) • Batching Job result storage • Online writing/reading • Persistence for Streaming Jobs • 99.95% available
  • 8. DiDi HBase Platform • HBase Version • Based on 0.98.21 • Region Group patch HBASE-6721 • Thrift2 patch • Multi-tenant Problem • A bad table can put down a cluster • We don’t know who the tables belong to
  • 9. DiDi HBase Platform • Region Group
  • 10. DiDi HBase Platform • Region Group • Isolate important use cases from others • Easy to manage(web ui, user group, operation tools) • Elastic to assign resources • Different Configuration in one Cluster(for different machine types, business, testing etc) • Easy to compute the cost of the business • Easy to upgrade the regionserver in one Group before do it in the whole cluster • Cost(share pool) = TableSize*x x = cost/GB • Cost(specific group ) = Rscount*y y = cost/RS
  • 11. DiDi HBase Platform • Improvement • Web UI to show group • MoveTables bug fix • CreateTableHandler fix
  • 13. DiDi HBase Platform • DiDi HBase Service
  • 14. DiDi HBase Platform Create Project and Tables
  • 16. DiDi HBase Platform Monitor your tables Get your bill, user must care for their cost
  • 17. DiDi HBase Platform • Phoenix • Advantage • Easy to use for RDBMS User(jdbc、sql) • Auto salting table for performance and hot spot avoiding • Like a Big Mysql(One sentence to explain to our users) • Disadvantage • Some bug like ordering vector item • Unstable statistic info caching • No good in Join case • So many other hotter system :Presto/Impala/Spark SQL/Kylin • Successful Use • Row Timestamp • Multidimensional Table Schema
  • 18. • Phoenix(more customers recently) • Row Timestamp for metrics • Monitoring table write/read/storage • Easy to compute avg, max, min for metrics • Quick to query recently data • Multi-dimension Table Schema • MR/Spark Job to compute BI reporting data • Many demission combination result like city, gender, age, business type • Primary Key: JobID, date, dimission1, dimission2, dimission3… • Value: dimNameArray, valueArray • This can fit nearly all the Multi-dimension reporting business DiDi HBase Platform
  • 19. DiDi HBase Platform • Client Access • Multiple Languages Clients • C++, Go, Python, PHP • Thritf2, QueryServer • Security(ACL)
  • 20. Application and Solution(Hadoop Monitor) • Hadoop Monitor • Help hadoop to query their fsimage and jobhistory • BI for Hadoop manager • Store data in phoenix
  • 23. Application and Solution • GPS • Query Model • Rowkey:ID+Timestamp • Rowkey:Reversed GeoHash+timestamp+ID • GeoHash • A index in two dimensions • Fit HBase rowkey prefect • Point 1: same prefix code result in a nearby place • Point 2: query rowkey prefix can location a region whose area decided by prefix length
  • 24. Application and Solution • GPS • GeoHash
  • 25. Application and Solution(Online Machine Learning) • ETA(Estimated Time of Arrival) • Origin data collection • ETL • Feature extraction • Storage • Model Training
  • 26. Application and Solution • ETA(Estimated Time of Arrival) • Training data by spark, every 30 minutes • Pick up data by city from HBase in 5 minutes • Compute ETA in 25 minutes • Rowkey: Salting+CityId+Type0+Type1+Type2+Timestamp • Columns: Order,Feature • Every day HBase data will be dumped into HDFS for offline training
  • 27. Application and Solution(Image) • Traffic in Cloud • High Volume Throughput, Little Read • Read via 8 Thrift nodes • Road traffic info • POI data • Heat-map • Write with Spark Job
  • 29. Challenges and future • More connect with other bigdata framework • Hive Phoenix/HBase Handler • Integration with hive • Use Hive sql to query phoenix • Easy to load data from hadoop cluster • Join with Hive table • Spark Phoenix/HBase Handler
  • 30. Challenges and future • More stable • hbase1.x upgrade • OLAP extends • Kylin • TPC-H Compare • Thrift load balancer • Auto Group balancer • More powerful DHS