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Host and Storage System Environment

Host and Storage System Environment. Chapter 2. Presented by: Anupam Mittal. Lecture 4. Storage Systems Environment: Components of a Storage System Environment. Chapter Objectives. Upon completion of this chapter, you will be able to: List components of storage system environment

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Host and Storage System Environment

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  1. Host and Storage System Environment Chapter 2 Presented by: Anupam Mittal

  2. Lecture 4 • Storage Systems Environment: Components of a Storage System Environment Storage System Environment

  3. Chapter Objectives Upon completion of this chapter, you will be able to: • List components of storage system environment • Host, connectivity and storage • List physical and logical components of hosts • Describe key connectivity options • Describe the physical disk structure • Discuss factors affecting disk drive performance Storage System Environment

  4. Lesson: Components of Storage System Environment Upon completion of this lesson, you will be able to: • Describe the three components of storage system environment • Host, Connectivity and Storage • Detail Host physical and logical components • Describe interface protocol • PCI, IDE/ATA and SCSI • Describe storage options • Tape, optical and disk drives Storage System Environment

  5. Group of Servers LAN Host • Applications runs on hosts • Hosts can range from simple laptops to complex server clusters • Physical components of host • CPU • Storage • Disk device and internal memory • I/O device • Host to host communications • Network Interface Card (NIC) • Host to storage device communications • Host Bus Adapter (HBA) Server Laptop Mainframe Storage System Environment

  6. Fast Speed Slow Low High Cost Storage Hierarchy – Speed and Cost CPU registers L1 cache L2 cache Magnetic disk RAM Optical disk Tape Components of a Host

  7. I/O Devices • Human interface • Keyboard • Mouse • Monitor • Computer-computer interface • Network Interface Card (NIC) • Computer-peripheral interface • USB (Universal Serial Bus) port • Host Bus Adapter (HBA) Components of a Host

  8. Logical Components of a Host Components of a Host

  9. Logical Components of the Host • Application • Interface between user and the host • Three-tiered architecture • Application UI, computing logic and underlying databases • Application data access can be classifies as: • Block-level access: Data stored and retrieved in blocks, specifying the LBA • File-level access: Data stored and retrieved by specifying the name and path of files • Operating system • Resides between the applications and the hardware • Controls the environment Storage System Environment

  10. Logical Storage LVM Physical Storage Logical Components of the Host: LVM • Responsible for creating and controlling host level logical storage • Physical view of storage is converted to a logical view by mapping • Logical data blocks are mapped to physical data blocks • Usually offered as part of the operating system or as third party host software • LVM Components: • Physical Volumes • Volume Groups • Logical Volumes Storage System Environment

  11. Volume Groups • One or more Physical Volumes form a Volume Group • LVM manages Volume Groups as a single entity • Physical Volumes can be added and removed from a Volume Group as necessary • Physical Volumes are typically divided into contiguous equal-sized disk blocks • A host will always have at least one disk group for the Operating System • Application and Operating System data maintained in separate volume groups Logical Volume Logical Disk Block Logical Volume Physical Volume 1 Physical Volume 3 Physical Volume 2 Physical Disk Block Volume Group Storage System Environment

  12. LVM Example: Partitioning and Concatenation Servers Logical Volume Physical Volume Partitioning Concatenation Storage System Environment

  13. Logical Components of the Host (Cont) • Device Drivers • Enables operating system to recognize the device • Provides APIto access and control devices • Hardware dependent and operating system specific • File System • File is a collection of related records or data stored as a unit • File system is hierarchical structure of files • Examples: FAT 32, NTFS, UNIX FS and EXT2/3 Storage System Environment

  14. File System: Metadata Examples UNIX (UFS) • File type and permissions • Number of links • Owner and group IDs • Number of bytes in the file • Last file access • Last file modification Windows (NTFS) • Time stamp and link count • File name • Access rights • File data • Index information • Volume information Components of a Host

  15. File Systems: Journaling and Logging • Improves data integrity and system restart time over non-journaling file systems • Uses a separate area called a log or journal • May hold all data to be written • May hold only metadata • Disadvantage - slower than other file systems • Each file system update requires at least 1 extra write – to the log Components of a Host

  16. File System Blocks Teacher (User) Course File(s) File System Files 1 2 3 Configures/ Reside in Mapped by a file Manages system to Disk Physical Extents Disk Sectors LVM Logical Extents 5 4 6 Managed by Consisting of Mapped by Residing in disk storage LVM to subsystem How Files are Moved to and from Storage Storage System Environment

  17. Module Summary Key points covered in this module: • Hosts typically have: • Hardware: CPU, memory, buses, disks, ports, and interfaces • Software: applications, operating systems, file systems, device drivers, volume managers • Journaling enables: • very fast file system checks in the event of system crash • provides better integrity for file system structure • HBAs are used to connect hosts to storage devices Components of a Host

  18. CPU HBA Cable BUS Disk Port Connectivity • Interconnection between hosts or between a host and any storage devices • Physical Components of Connectivity are: • Bus, port and cable Storage System Environment

  19. Bus Technology Serial Serial Bi-directional Parallel Connectivity

  20. Bus Technology • System Bus – connects CPU to Memory • Local (I/O) Bus – carries data to/from peripheral devices • Bus width measured in bits • Bus speed measured in MHz • Throughput measured in MB/S Connectivity

  21. DirectlyAttachedEntities Network ConnectedEntities Tightly ConnectedEntities Connectivity Protocol • Protocol = a defined format for communication between sending and receiving devices • Tightly connected entities such as central processor to RAM, or storage buffers to controllers (example PCI) • Directly attached entities connected at moderate distances such as host to storage (example IDE/ATA) • Network connected entities such as networked hosts, NAS or SAN (example SCSI or FC) Storage System Environment

  22. Host Apps Operating System PCI SCSI or IDE/ATA Device Drivers Communication Protocols Connectivity

  23. Popular Connectivity Options: PCI • PCI is used for local bus system within a computer • It is an interconnection between microprocessor and attached devices • Has Plug and Play functionality • PCI is 32/64 bit • Throughput is 133 MB/sec • PCI Express • Enhanced version of PCI bus with higher throughput and clock speed • V1: 250MB/s • V2: 500 MB/s • V3: 1 GB/s Storage System Environment

  24. Popular Connectivity Options: IDE/ATA • Integrated Device Electronics (IDE) / Advanced Technology Attachment (ATA) • Most popular interface used with modern hard disks • Good performance at low cost • Inexpensive storage interconnect • Used for internal connectivity • Serial Advanced Technology Attachment (SATA) • Serial version of the IDE /ATA specification • Hot-pluggable • Enhanced version of bus provides upto 6Gb/s (revision 3.0) Storage System Environment

  25. Popular Connectivity Options: SCSI • Parallel SCSI (Small computer system interface) • Most popular hard disk interface for servers • Supports Plug and Play • Higher cost than IDE/ATA • Supports multiple simultaneous data access • Used primarily in “higher end” environments • SCSI Ultra provides data transfer speeds of 320 MB/s • Serial SCSI • Supports data transfer rate of 3 Gb/s (SAS 300) Storage System Environment

  26. SCSI - Small Computer System Interface • Most popular hard disk interface for servers • Higher cost than IDE/ATA • Supports multiple simultaneous data access • Currently both parallel and serial forms • Used primarily in “higher end” environments Connectivity

  27. SCSI Model Target Initiator Connectivity

  28. LUNs Target ID Initiator ID SCSI Model Connectivity

  29. LUN Initiator ID Target ID SCSI Addressing • Initiator ID - a number from 0 to 15 with the most common value being 7. • Target ID - a number from 0 to 15 • LUN - a number that specifies a device addressable through a target. Connectivity

  30. t0 LUNs PeripheralController d0 d1 d2 Target c0 – Controller/Initiator/HBA Disk Identifier - Addressing c0 t0 d0 Host Addressing • Controller • Target • LUN Connectivity

  31. SCSI - Pros and Cons • Pros: • Fast transfer speeds, up to 320 megabytes per second • Reliable, durable components • Can connect many devices with a single bus, more than just HDs • SCSI host cards can be put in almost any system • Full backwards compatibility • Cons: • Configuration and setup specific to one computer • Unlike IDE, few BIOS support the standard • Overwhelming number of variations in the standard, hardware, and connectors • No common software interfaces and protocol Connectivity

  32. Comparison IDE/ATA vs. SCSI Feature IDE/ATA SCSI Internal and External Storage Connectivity Market Internal Storage 320 Speed (MB/sec) 100/133/150 Yes Hot Pluggable No Very good but veryexpensive to set up Expandability Easier to set up High cost/Fasttransfer speed Cost/Performance Good Connectivity

  33. Physical Components – Host with External Storage Port Bus CPU Host HBA Cable Port Disk Connectivity

  34. Host Apps DBMS Mgmt Utils File System LVM Multipathing Software Device Drivers HBA HBA HBA Fibre Channel Storage Arrays Fibre Channel Connectivity

  35. External Storage Interfaces – A Comparison • SCSI • Limited distance • Limited device count • Usually limited to single initiator • Single-ported drives • Fibre Channel • Greater distance • High device count in SANs • Multiple initiators • Dual-ported drives Connectivity

  36. External Storage Interfaces – A Comparison • iSCSI • Transport is over an IP network • SCSI Commands are exchanged over an IP network • Fibre Channel over Ethernet • Tunnels fibre channel commands over IP Connectivity

  37. Fibre Channel Connectivity Hosts Storage Switches Connectivity

  38. Storage: Medias and Options • Magnetic Tape • Low cost solution for long term data storage • Limitations • Sequential data access, Single application access at a time, Physical wear and tear and Storage/retrieval overheads • Optical Disks • Popularly used as distribution medium in small, single-user computing environments • Write once and read many (WORM): CD-ROM, DVD-ROM • Limited in capacity and speed • Disk Drive • Most popular storage medium with large storage capacity • Random read/write access • Ideal for performance intensive online application Storage System Environment

  39. Lesson Summary Key points covered in this lesson: • Host components • Physical and Logical • Connectivity options • PCI, IDE/ATA, SCSI • Storage options • Tape, optical and disk drive Storage System Environment

  40. Lecture 5 • Disk drive components, Disk Drive Performance Storage System Environment

  41. Lesson: Disk Drive Upon completion of this lesson, you will be able to: • List and discuss various disk drive components • Platter, spindle, read/write head and actuator arm assembly • Discuss disk drive geometry • Describe CHS and LBA addressing scheme • Disk drive performance • Seek time, rotational latency and transfer rate • Law’s governing disk drive performance • Enterprise flash drive Storage System Environment

  42. Controller HDA Interface Power Connector Disk Drive Components Storage System Environment

  43. Disk Drive Components: Platters 01010100111010101010 00110100111010101010 00110100111010101010 10110101011010101010 Physical Disks

  44. Disk Drive Components: Spindle Spindle Platters Physical Disks

  45. Disk Drive Components: Read/Write Heads Physical Disks

  46. Disk Drive Components: Actuator Spindle Actuator Physical Disks

  47. Physical Disk Structures: Actuator Arm Assembly R/W Head R/W Head Actuator Physical Disks

  48. Disk Drive Components: Controller Controller Interface HDA Power Connector Bottom View of Disk Drive Physical Disks

  49. Physical Disk Structures: Sectors and Tracks Sector Track Platter Physical Disks

  50. Platter Geometry and Zoned-Bit Recording Sector Track Platter Without Zones Platter With Zones Physical Disks

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