Hitachi Path Management & Load Balancing with Hitachi Dynamic Link Manager and Global Link Availability Manager

Transcription

1 Hitachi Data System s WebTech Series Hitachi Path Management & Load Balancing with Hitachi Dynamic Link Manager and Global Link Availability Manager

2 The HDS WebTech Series Dynamic Load Balancing Who should attend: Systems and Storage Administrators Storage Specialists & Consultants IT Team Lead System and Network Architects IT Staff Operations and IT Managers Others who are looking for storage management techniques 2

3 Learning Objectives Upon completion of this seminar, you should be able to: Describe the primary purposes of path management software Diagram the critical path of data storage input and output with Hitachi enterprise storage Explain the complimentary roles of Dynamic Link Manager & Global Link Availability Manager Describe the load balancing algorithms available Use Dynamic Link Manager and / or Global Link Availability Manager to select the most appropriate algorithm Describe path management recommended practices Describe how to develop greater storage management expertise 3

4 FC SAN Topology 4

5 Enterprise Storage System 5

6 FC SAN I/O Path Host Storage System Application DEV LU I/O Request HBA Fiber Cable Port CHA 6

7 Path Management Defining the path of the data I/O Always starts at the application Moves to the storage system Returns to the application Storage Port CHP Cache ACP/DKC Parity Group Disk App HBA / Host Switch Storage System 7

8 Path Management Critical path management issues Fail-over fall-back Optimizing (balancing) the I/O load I/O characteristics (random, sequential, reads, writes) Storage Port CHP Cache ACP/DKC Parity Group Disk App HBA / Host Switch Storage System 8

9 Path Failover and Failback Server Server Applications Applications HDLM HDLM Failure Standby Failure Reduction of Balancing Paths Volume Volume Storage Simple Failover Storage With Load Balancing Dynamic Link Manager software provides continuous storage access and high availability by distributing I/O over multiple paths Failover and fallback in either manual or automatic modes Automated path health checks Allows dynamic LUN addition and deletion without a server reboot * * O/S and array dependent, check system requirements for details 9

10 Load Balancing Server Server Applications Regular Driver Applications HDLM I/O Bottleneck Load Balancing Storage Volumes Storage Volumes Without Load Balancing With Load Balancing Dynamic Link Manager software distributes storage access across multiple paths to improve I/O performance with load balancing Bandwidth control at the HBA level - and in conjunction with Global Link Availability Manager at the LUN level. 10

11 I/O Scheduling and Processing Life of an I/O Operation 11

12 Life of an I/O Operation 350 ms (.35 sec) 1 CPU Time Queue Time I/O Time 25% 15% 60% Review of an application transaction This is typical for OLTP (Online Transaction Processing) , DSS, and Rich Media have higher % of I/O content OLAP, CRM, and ERP have higher % of CPU content ms is an example only this does not include network time (LAN or WAN) 12

13 Life of an I/O Operation The Role of the I/O The I/O component plays an important role in overall transaction response time in many transaction types. I/O response time must be monitored on an ongoing basis to insure customer satisfaction. When the overall transactional response time shows degradation, the first element to be blamed is the I/O subsystem. Now Let s look at the various stops of a tumultuous I/O journey. 13

14 Storage Systems Groups Storage System Back-End External Storage System 14 Storage System Port Cache Core Director Life of an I/O Operation I/O Journey Edge Switch Host Bus Adapter Application The I/O journey starts and ends at the application

15 I/O Cache Management Cache Management Nomenclature Multiple queues are used in Hitachi storage systems We will look at the general LRU queue The frames on a LRU queue: MRU position Most Recently Used LRU position Least Recently Used Cache Demotion Time: Time to travel from MRU to LRU position of the queue This can be improved by: Increasing cache size Using intelligent caching algorithms Cache Residency Time: Total time a track resides in cache Value for residency time goes from the Demotion Time value to the infinite MRU LRU LRU Queue 15

16 Random Read Processing 1. When a random read request is received from the host, the Front-End Director (FED) accesses the cache directory (Control Memory/Cache Meta Data) and performs a directory search to see if the requested record is in cache. 2. If the record is in cache, it is sent to the host from cache. The read hit ratio is important for OLTP overall response time. 3. If the record is not present, the Back-End Director (BED) schedules a read from the disk location. The record is loaded into the cache from there it is transferred to the host. To hosts F E D F E D C M Cache B E D 16

17 Sequential Read Processing 1. The first steps are the same as a random read 2. When the FED receives requests for sequential records, a sequential pattern is detected (sequential detect) 3. NSRs from the next tracks are preloaded into cache. Following requests will be satisfied through cache 4. In this type of I/O request, the Read Hit Ratio should always be over 85% 5. Performance is typically very good on all Hitachi storage systems for sequential read To hosts F E D F E D C M Cache B E D 17

18 Random Write Processing 1. The port receives a write operation from the host 2. Two copies of the updated record are written into cache onto two different memory boards under the NVS line 3. The frame is queued on a specialized queue (dirty queue) for destage scheduling. At low NVS line value, back-end activity is reduced by keeping frames on the dirty queue (more writes per de-stage operation) for a longer period 4. When the frame arrives at the LRU position, it gets written to the disk 5. The other copy of the updated record is kept in cache and placed on the General LRU queue. This is to increase the Read Hit Ratio in case of subsequent read or write request to the same record To hosts F E D F E D C M 18

19 Sequential Write Processing 1. The port receives a write operation from the host 2. Two copies of the updated record are written into cache onto two different memory boards under the NVS line 3. When sequential records are received, a sequential pattern is detected 4. All following records are kept in cache 5. When a full stripe (or more) has been received, the parity track is created in cache and the entire stripe is written to the disks in one logical revolution To hosts C H I P C H I P C M All frames are sent to the free queue 19

20 Round Robin Extended Round Robin 20

21 Round Robin Extended Round Robin Impact of ExRR Versus RR on Sequential Detect Server Dynamic Link Manager software RR Storage Not Sequential Server Dynamic Link Manager software ExRR Storage Sequential 21

22 On-line Demonstration of Path Management 22

23 Dynamic Link Manager Enables fault-tolerant access to data on Hitachi and EMC storage systems for direct-attached storage (DAS) and storage area network (SAN) environments. Path failover and I/O balancing over multiple host bus adapter (HBA) cards Improves performance by distributing and balancing loads across multiple paths Improves application availability by automatically switching the path in the event of failure UNIX/Linux Windows 23

24 Global Link Availability Manager Servers LAN SAN Console Hitachi storage system HiCommand Global Link Availability Manager add-on provides single point management of all Dynamic Link Manager connections in SAN 24

25 Load Balancing in a Clustered Environment Windows Microsoft Cluster Server Oracle RAC Veritas Cluster Server Sun Solaris Sun Cluster VERITAS Cluster Server Oracle RAC HP-UX MC/Serviceguard Oracle RAC AIX HACMP Veritas Custer Server Oracle RAC Linux Redhat AS Bundle Cluster SuSE Linux Bundle Cluster Veritas Cluster Server Oracle RAC Active Host HBA Storage HDLM Load Balance CHA HBA Cluster LUN Standby Host HBA HDLM CHA HBA 25

26 HiCommand Global Link Availability Manager HiCommand Global Link Availability Manager Features Path management Event notification Group management Shared common HiCommand Suite user interface and base components 26

27 Global Link Availability Manager Features Manage the entire Dynamic Link Manager multi-pathing environment from a single console For each Dynamic Link Manager instance list path information for all paths or for each host, HBA port, storage system, and storage port. Aggregated path views corresponding to path status (online or offline) check the health of the entire multi-pathing environment. Adjust the online / offline path status for single or multiple hosts Adjust load balancing for individual LUNs Group Management Control access to a specific group of hosts (subset of Dynamic Link Manager instances). Allows managing a subset of hosts as a single unit Resource Groups enable System Administrators to securely manage their own set of hosts. Host Groups lets individual administrators create customized management views tailored to fit their own operational needs. 27

28 Global Link Availability Manager 28

33 Recommended Practices Understand the I/O characteristics of your applications Applications generating sequential I/O: Extended Round Robin Applications generating random I/O: Round Robin If managing 10 or more hosts, use Global Link Availability Manager Update latest release of HDLM Always review latest release notes & user guides Use 4 adapters typically best balance of performance & availability (deeper queue depths greater scalability) Zone HBA to storage port Use switches from same vendor in same SAN fabric Backup license key 33

34 Next Steps Training: CCI0110 Basic Storage Concepts TCC0260 Introduction to Dynamic Link Manager & Global Link Availability Manager (computer-based training) TSI0595 Dynamic Link Manager / Global Link Availability Manager TSI0596-Dynamic Link Manager TSI0590ーGlobal Link Availability Manager TSI Managing Storage Performance with Hitachi Tuning Manager HDS Professional Certification HDS Certified Professional (Foundations) HDS Certified Storage Manager White Papers: Use the RSS feed to automatically update with latest technical white papers 34

35 Upcoming WebTech Sessions: 22 August - Optimal Storage Performance for Microsoft Exchange 12 September - RAID Concepts 19 September - Enterprise Data Replication Architectures that Work: Overview and Perspectives 35

36 Thanks!