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Oracle 10 g Database Storage Demystified

Oracle 10 g Database Storage Demystified. Jeff Browning, O.C.P, R.H.C.A. Senior Manager Network Appliance, Inc. OracleWorld 2003 San Francisco. Agenda. A little history The notion of storage networking SAN and NAS Current-technology SAN: FCP Current-technology NAS: IP over GbE

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Oracle 10 g Database Storage Demystified

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  1. Oracle 10gDatabase StorageDemystified Jeff Browning, O.C.P, R.H.C.A.Senior ManagerNetwork Appliance, Inc. OracleWorld 2003 San Francisco

  2. Agenda • A little history • The notion of storage networking • SAN and NAS • Current-technology SAN: FCP • Current-technology NAS: IP over GbE • RAID: The “packaging” of hard disks • RAID0 • RAID1 • RAID4 • RAID5 • Combinations of RAID levels • Emerging storage technologies • ATA RAID • Serial ATA (SATA) • iSCSI • NFS v. 4 (NFS RDMA) • Conclusion and wrap up

  3. A Little History • IDE/ATA: The beginning • SCSI: A proliferation of standards • SCSI-1 • SCSI-2: The proliferation begins • SCSI-3: A new approach

  4. In the BeginningThere Was IDE/ATA • Introduced by IBM with the AT/PC in 1984 • Supported a master/slave concept • Enhanced and adopted by Compaq in 1986 with the Deskpro 386 as the IDE interface • ATA and IDE are now interchangeable terms

  5. What You Could Dowith an IDE/ATA Device:Not Much • IDE/ATA was slow (4 MB/s to start) • It didn’t support many devices(usually 2 hard drives) • It wasn’t reliable • But it was, and remains, very, very cheap • It was never used widely for databases

  6. SCSI: A Proliferation of Standards • Invented by Alan Shugart(founder of Seagate) in 1979 • Adopted as an ANSI standard in 1986 • First version was referred to as SCSI-1

  7. What You Could Dowith a SCSI-1 Device:A Bit More • SCSI-1 was still pretty slow (5 MB/s) • It supported 7 peripheral devices • It was more reliable than IDE/ATA • It was also more expensive • This was the first choice for Sun, HP and other open systems vendors and, notably, the Macintosh

  8. SCSI-2: The Proliferation Begins • Fast SCSI: Higher transfer speed(10 MB/s or higher) • Wide SCSI: Width of the bus wasincreased from 16 to 32 bits • More devices per bus (from 7 to 15) • Other improvements • Improved cables and connectors • Improved signaling • Active termination

  9. SCSI-3: A New Approach • With SCSI-3 the approach changed • Cabling and connection layer no longerdefined in the basic spec • So-called “interconnect” or “physicallayer” standards • SCSI-3 basic spec only defines acommand set and a communication protocol

  10. SCSI-3: The PhysicalLayer Standards

  11. The Notion of Storage Networking • SCSI provided a way to attach disks to a host • The need for sharing of disk and tape backup resources led to the idea of“shared SCSI”

  12. Storage Networking for Applications • Certain applications required shared disk • Shared SCSI evolved as a way to solve this problem

  13. Storage Networking Evolves • Storage networking evolved along two paths • SAN: With FCP being the dominant protocol • NAS: With Gigabit Ethernet (GbE) NAS became a viable alternative to FCP for many applications • The next section discusses the tradeoffs between these approaches

  14. SAN and NAS • Storage Area Networks (SAN) take the approach of making SCSI sharable • Network Attached Storage (NAS) uses existing file sharing protocols to connect databases to storage • Both approaches have their place: They are different

  15. Fibre Channel Emerges as Dominant SAN • Fibre Channel was designed as a SAN protocol • It was adopted as an ANSI standard in 1994 • It has emerged as the de facto standard for creating a SAN

  16. Typical Fibre Channel SAN

  17. Fibre Channel SAN Tradeoffs • Advantages • Bandwidth is good: 2 Gb FC is now common • Host CPU cost per I/O is comparable to SCSI • Latency is low and performance is good • Scalability is good • Disadvantages • More expensive than comparable IP network • Interoperability is poor but improving • Highly complex to setup and administer • Difficult to share disk capacity

  18. NAS Emerges as Alternative to SAN • NFS was created by Sun in in the early 1980s • Version 1 of NFS was widely regarded as inappropriate as a file sharing protocol for databases • Version 2 improved enough that Oracle certified NFS for Oracle datafiles in 1997 • Version 3 builds upon those improvements • Version 4 is emerging (more on this later)

  19. Typical IP/GbE NAS

  20. IP/GbE NAS Tradeoffs • Advantages • Bandwidth is pretty good using GbE • Switches/NICs are very inexpensive compared to FC switches/HBAs • Simple and easy to setup and administer • Interoperability is excellent • Disk capacity can be easily shared – even across platforms • Disadvantages • Host CPU cost may be higher than FC, depending on load, but not if the load is spindle-bound (NFS v. 4 fixes this in spades) • CPU Scalability (in the sense of CPU count)can be lower than FC (again NFS v. 4 addresses this)

  21. SAN vs. NAS Suitability • SAN • Suitable for high-end environments where latency, performance, or CPU cost per I/O are critical • Required by some applications where NAS is not supported • NAS • Suitable for low- or mid-end environments where performance or CPU cost is less important than$$ cost • Also suitable for some high-end environments where CPU is compute intensive, not I/O intensive • SAN and NAS are converging

  22. RAID: Redundant Array of Inexpensive Disks • The problem: • Disks are fragile; they fail • Data is precious and must be protected • Tape or disk backup is too slow or too expensive • RAID provides a way to combine disks together with redundancy so that a single disk failure will not lose data • Hot spares and auto-promotion make this a viable long-term solution • Software RAID vs. hardware RAID

  23. RAID and Its Variants

  24. RAID0: Striping

  25. RAID0 Tradeoffs • Advantages: • Fastest type of RAID; leverages disks well • No disk overhead • Disadvantage: • A single disk loss is critical • Suitability • Any environment where performance is important, and you do not care about the data, e.g. Datamarts

  26. RAID1: Simple Mirroring

  27. RAID1: Simple Mirroring

  28. RAID1 Tradeoffs • Advantages: • Read capacity is higher than single disk (but lower than striping) • Very fault tolerant; all data is mirrored • Disadvantage: • Single disk capacity for writes • Two write per I/O penalty • Doubles disk cost • Suitability: • Very commonly used for online redo logs

  29. RAID0+1: Striping with Mirroring

  30. RAID0+1: Striping with Mirroring

  31. RAID1+0: Mirroring with Striping

  32. RAID1+0: Mirroring with Striping

  33. RAID0+1/RAID1+0 Tradeoffs • Advantages: • Read capacity is high; multiple disks are leveraged • Very fault tolerant; all data is mirrored • Disadvantage: • Two write per I/O penalty • Doubles disk cost • Suitability: • Very common for storing Oracle datafiles where redundancy is highly valued

  34. RAID4: Striping with Parity Disk

  35. RAID4: Striping with Parity Disk

  36. RAID4 Tradeoffs • Advantages: • Read Capacity is high; multiple disks are leveraged • Low RAID overhead; almost as good as RAID 0 • RAID protection exists • Disadvantage: • Two disks cannot be lost • Parity disk can become a bottleneck (some vendors avoid this issue with buffering, in which case performance is similar to RAID 1) • Suitability: • Very common for storing Oracle datafiles where redundancy is needed, and the cost of RAID0+1/RAID1+0 is too high

  37. RAID5: Striping with Striped Parity

  38. RAID5: Striping with Striped Parity

  39. RAID5 Tradeoffs • Advantages: • Read Capacity is high; multiple disks are leveraged • Low RAID overhead; almost as good as RAID 0 • RAID protection exists • Disadvantage: • Two disks cannot be lost • Slowest RAID; CPU cost of parity striping is high • Suitability: • Very common for storing Oracle datafiles where redundancy is needed, performance is not critical, and the cost of RAID0+1/RAID1+0 is too high

  40. Emerging Storage Technologies • ATA RAID • Serial ATA (SATA) • iSCSI • NFS v. 4 (NFS RDMA)

  41. ATA RAID • A repackaging of cheap ATA/IDE disks • Used as a tape backup substitute • Archive storage is on-line and accessible • Faster than tape • Almost as cheap as tape, or even cheaper if compression is used

  42. Serial ATA • An updating of the ATA/IDE spec to current technology • Intel and Dell • Targeted for desktops and next generation storage appliances • Could become a serious competitor to FCP and serial bus SCSI

  43. iSCSI • Implements SCSI-3 protocol over IP networks • Intel is a leader • Software initiators exist for Windows and Linux • HP-UX and AIX initiators are in public beta • Targets are available from a variety of vendors • Presently immature, but will become viable competitor to FCP • Key is TOE HBAs on both target and initiator • Effectively offloads host/target CPU from IP traffic • Cost per port for switches and HBAs is vastly cheaper than FCP • If performance becomes comparable, FCP could be toast

  44. Typical iSCSI SAN

  45. NFS v. 4 (NFS RDMA) • Basically, a rewrite of NFS • Focused on “local sharing” i.e., database customers and the like, who need to share data across a small, focused network with very good performance • Supports Read Direct Memory Access, a very high performance, low latency I/O protocol • Supports Infiniband as an I/O interface • Leaders are Network Appliance and Sun • Will provide a transparent performance upgrade path for NFS database customers

  46. Agenda • A little history • The notion of storage networking • SAN and NAS • Current-technology SAN: FCP • Current-technology NAS: IP over GbE • RAID: The “packaging” of hard disks • RAID0 • RAID1 • RAID4 • RAID5 • Combinations of RAID levels • Emerging storage technologies • ATA RAID • Serial ATA (SATA) • iSCSI • NFS v. 4 (NFS RDMA) • Conclusion and wrap up

  47. Wrap Up

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