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Storage Primer


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Storage basics, SAN, NAS, data protection, security

Published in: Technology

Storage Primer

  1. 1. Storage Primer Sriram Ranganathachari
  2. 2. What is Storage ? <ul><li>Primary storage disk or RAM </li></ul><ul><li>Secondary storage tape or Disk </li></ul><ul><li>Storage can be online, nearline or offline </li></ul><ul><ul><ul><li>• Online – Random-access, low wait time – disk </li></ul></ul></ul><ul><ul><ul><li>• Nearline – Random-access, some wait time – disk </li></ul></ul></ul><ul><ul><ul><li>• Offline – Sequential-access, long wait time – tape </li></ul></ul></ul><ul><li>Offline and nearline storage </li></ul><ul><ul><ul><li>• File restore </li></ul></ul></ul><ul><ul><ul><li>• Image restore </li></ul></ul></ul><ul><ul><ul><li>• Data archiving </li></ul></ul></ul>
  3. 3. Evolution of Storage Performance/Reliability/Management Time/Complexity Storage Today Ethernet Internal Storage Direct-Attach Storage (DAS) Network-Attached Storage (NAS) Storage Area Network (SAN)
  4. 4. Need For the Invention of SAN <ul><li>Storage market Demand was growing and the traditional Server Attached Storage called DAS was not able to meet the High end Requirements . </li></ul><ul><li>Rapid storage growth is causing new types of problems for data center managers </li></ul><ul><li>Advantages of SAN </li></ul><ul><ul><li>Staff and skill shortages </li></ul></ul><ul><ul><li>Providing investment protection while at the same time storage prices drop </li></ul></ul><ul><ul><li>Server, storage and data consolidations are often planned, or worse are in parallel </li></ul></ul><ul><ul><li>Enterprise SAN and Storage Management is required </li></ul></ul><ul><ul><li>Investment justification with limited fiscal resources </li></ul></ul>
  5. 5. Disadvantages of SCSI <ul><li>Number of devices that can be attached on a </li></ul><ul><li>Single bus is very limited </li></ul><ul><li>To reconfigure one device all the devices in </li></ul><ul><li>the string must be brought offline . </li></ul><ul><li>Distance limitation due to cable length . </li></ul><ul><li>Speed limitations </li></ul><ul><li>Sharing is possible by Multi-Drop Configuration BUT : </li></ul><ul><li>All devices can not transfer data at the same time </li></ul><ul><li>Uses Arbitration </li></ul><ul><li>During Arbitration – No Data Transfer </li></ul>
  6. 6. RAID
  7. 7. Advantages of SAN over SCSI <ul><li>Removes traditional Server-Storage connection </li></ul><ul><li>High Speed of Communication </li></ul><ul><li>Can connect Devices up to 10 Km </li></ul><ul><li>Number of devices that can be connected is very high (16 million ) </li></ul><ul><li>Improved backup and recovery </li></ul><ul><li>LAN free and server free data movement </li></ul><ul><li>Centralized management </li></ul><ul><li>Disk Storage can be expanded without disrupting the servers </li></ul>
  8. 8. Some more benefits <ul><li>Increased disk utilization </li></ul><ul><li>Deferring disk procurement </li></ul><ul><li>Reduce data center rack/floor space </li></ul><ul><li>Tape procurement deferral </li></ul><ul><li>New DR capabilities </li></ul><ul><li>Improved DR capabilities </li></ul><ul><li>On-line recoverability options </li></ul><ul><li>Staff Utilization for Server Management </li></ul><ul><li>TB-per-DBA ratio decline </li></ul><ul><li>Mgmt costs as a % of storage costs </li></ul><ul><li>Improved overall availability </li></ul><ul><li>Increased life of current disk </li></ul><ul><li>Reduction of UNIX & NT Servers </li></ul><ul><li>LAN/WAN performance </li></ul><ul><li>Improve/Protect critical data </li></ul><ul><li>Increase I/O performance, bulk data movement </li></ul><ul><li>Reduced Storage Maint. </li></ul><ul><li>Reduce backup servers </li></ul><ul><li>Reduce/eliminate batch, backup windows </li></ul><ul><li>Non-disruptive scalability </li></ul><ul><li>Avoid Data Area Network growth </li></ul><ul><li>Impact new/migrating apps </li></ul><ul><li>Impact to applications development, testing </li></ul><ul><li>Extending Life of Servers </li></ul><ul><li>Reduce CPU Load on Servers </li></ul><ul><li>Support Server Clustering </li></ul><ul><li>Secondary Security Services </li></ul><ul><li>Vendor Consolidation </li></ul><ul><li>Storage On-Demand </li></ul>
  9. 9. Fundamental difference between SAN and NAS <ul><li>SAN </li></ul><ul><li>A SAN is a shared &quot;network&quot; of storage </li></ul><ul><li>• Block access to LUNs </li></ul><ul><li>• Online and offline storage </li></ul><ul><li>• SAN device = storage array </li></ul><ul><li>Protocol: </li></ul><ul><li>SCSI over Fibre Channel </li></ul><ul><li>SCSI over IP/Ethernet (iSCSI) and FC </li></ul><ul><li>NAS </li></ul><ul><li>NAS is a file system shared over a network </li></ul><ul><li>• File access to data </li></ul><ul><li>• Online storage only </li></ul><ul><li>• NAS device = File server or &quot;filer&quot; </li></ul><ul><li>Protocol: </li></ul><ul><li>NFS, CIFS over IP over Ethernet </li></ul>
  10. 10. What is Fibre Channel ? <ul><li>Fibre Channel is serial interconnection technology that was developed to bring together elements from the channel and networking technology . </li></ul><ul><li>It Provides : </li></ul><ul><li>Reliable High Speed Communication </li></ul><ul><li>Data transport over longer distances </li></ul><ul><li>Low Overhead communication </li></ul><ul><li> </li></ul>
  11. 11. What is SAN <ul><li>SAN is dedicated network behind the servers , based on Fibre Channel architecture . </li></ul>
  12. 12. How SAN works <ul><li>The data from a host server is converted into optical light pulses by a “host bus adapter” in the server, the pulses are transmitted over fiber-optic cables, through a switched network, to an intelligent storage array, which uses advanced raid protected disk drives to store the data safely. </li></ul><ul><li>The act of using a network to create a shared pool of storage devices is what makes a SAN different from the way data was normally stored on computers. The network is used to move data between various storage devices, allows for data sharing between different servers, and provides a fast medium for backing up and restoring data. </li></ul><ul><li>Devices in a SAN are usually bunched closely together in a single room, but the network allows the devices to be connected over long distances. The ability to spread everything out over long distances makes a SAN very useful to large companies with many offices. </li></ul>
  13. 13. SAN implementation
  14. 14. Who should buy SAN <ul><li>Database servers: Oracle, Sybase, SQL, DB2, Informix, and other database servers </li></ul><ul><li>File servers: Using SAN-based storage for file servers lets you expand file server resources quickly, makes them run better, and enables you to manage your file-based NAS storage through the SAN. </li></ul><ul><li>Backup servers: SAN-based backup is dramatically faster than LAN-based backup. </li></ul><ul><li>Voice/video servers: Voice and video servers tend to push large amounts of data very quickly. </li></ul><ul><li>Mail servers: Using SAN-based storage for mail servers enables quick restoration of data in case of corruption or viruses. </li></ul><ul><li>High-performance application servers: Applications such as document management, customer relationship management, billing, data warehouses, and other high-performance and critical applications all benefit by what a SAN can provide. </li></ul>
  15. 15. SAN Segments <ul><ul><li>PARTS </li></ul></ul><ul><ul><li>Host Layer- HBA, Drivers, Pathing sofware, OS </li></ul></ul><ul><ul><li>Fabric Layer- Hubs and switches, fabric os, cabling </li></ul></ul><ul><ul><li>Storage Layer- Tapes and disks, advanced storage software </li></ul></ul><ul><ul><li>PLAYERS : </li></ul></ul><ul><ul><li>EMC, IBM,HITACHI, NetApp,Sun, HP, Veritas etc </li></ul></ul>
  16. 16. SAN Components HBA CARD Tape Library Fibre Cables Storage Arrays
  17. 17. Naming and Addressing Scheme <ul><li>WWN : World Wide Name </li></ul><ul><li>A Unique 64 bit Address Assigned to the Node by manufacturer </li></ul><ul><li>WWPN : World Wide Port Name </li></ul><ul><li>A unique 64 Bit Address assigned to the N_Port </li></ul>
  18. 18. SAN Topologies <ul><li>Point to Point </li></ul><ul><li>Arbitrated Loop </li></ul><ul><li>Switched Fabric </li></ul>
  19. 19. Point to Point Topology <ul><li>Direct Connection between two N_Ports </li></ul><ul><li>No Sharing of Media </li></ul><ul><li>Allows Devices to use Full Bandwidth </li></ul><ul><li>Before the transmission two N_Ports perform a Login to assign the N_Port Address </li></ul>
  20. 20. Point to Point Connection
  21. 21. Arbitrated Loop Topology <ul><li>A loop of 127 Ports ( 126 NL_Port , 1FL_Port ) </li></ul><ul><li>The Bandwidth is shared by the Active Nodes </li></ul><ul><li>Media Access is gained through an Arbitration Protocol </li></ul><ul><li>Can Connect Ports up to a distance of 10 Km </li></ul>
  22. 22. Arbitrated Loop
  23. 23. FC - Switched Multi Switch Single Fabric Single Switch Fabric Array Array Array Array Array Array Array Array
  24. 24. Deployment: Switches vs. Directors Director Director Director Director Director Director 8–64 64–256 256–1024 Least Complexity Highest Availability Lowest Acquisition Cost Number of Hosts Switch Switch Switch Switch Switch Switch
  25. 25. Ports <ul><li>N_Port Node Point-to-point or fabric </li></ul><ul><li>NL_Port Node Node connected to an arbitrated loop </li></ul><ul><li>F_Port Fabric Fabric port </li></ul><ul><li>FL_Port Fabric Fabric connected to an arbitrated loop </li></ul><ul><li>L_Port Loop Hub port on an arbitrated loop </li></ul><ul><li>T_Port Fabric Trunk port between switches </li></ul><ul><li>E_Port Fabric Inter-switch Link connection </li></ul><ul><li>G_Port Fabric Unused switch port </li></ul>
  26. 26. IP Storage
  27. 27. iSCSI <ul><li>Enables access of DAS over IP Infrastructure </li></ul><ul><li>Optimal utilization of resource </li></ul><ul><li>Virtualized Storage </li></ul><ul><li>To enable FC based storage to be accessed through IP infrastructure </li></ul><ul><li>Block level storage from SAN accessed through iSCSI </li></ul><ul><li>IP Based Storage Protocol </li></ul>
  28. 30. ZONING Definition :Zoning is a logical separation of traffic between host and resources Advantages of Zoning · Data Integrity · Security · Shorter boot-up Types of Zoning : Soft zoning or name server zoning : done using a name server databases in the SAN director. Zoning is via port numbers and WWN numbers.  Hard zoning : Uses a routing table in the director, which assigns devices to zones only by WWN. This is more limited since it doesn't take the port number into consideration, which makes it harder to shift devices between ports.
  29. 32. ISL - Distance and Cables <ul><li>Operating distances decrease when moving from 1Gbps to 2Gbps </li></ul><ul><li>Media options </li></ul><ul><ul><li>Multi-mode </li></ul></ul><ul><ul><li>Single-mode </li></ul></ul><ul><ul><li>DWDM </li></ul></ul><ul><li>ISL design parameters </li></ul><ul><ul><li>Capacity </li></ul></ul><ul><ul><li>Distance </li></ul></ul><ul><ul><ul><li>Signal loss </li></ul></ul></ul><ul><ul><ul><li>Throughput </li></ul></ul></ul><ul><ul><ul><li>Power </li></ul></ul></ul>Multi-mode 1Gb=500m 2Gb=300m Single-mode > 10Km DWDM < 200Km >10km >10km 1Gbps 2Gbps 9 micron Single mode ~300m ~150m 1gbps 2Gbps 62.5 micron Multimode 500m 300m 1Gbps 2Gbps 50 micron Multimode Operating Distance Port Speed Fibre Optic Glass Filament Core
  30. 33. DWDM <ul><li>Data are carried at different wavelengths over fiber links </li></ul><ul><li>Different data formats can be transmitted together (e.g. IP, ESCON SRDF, Fibre Channel SRDF) </li></ul><ul><li>DWDM topologies include Point-to-Point and Ring configurations </li></ul>Transmission on fibre Combining Signals Separating Signals Transmitters Receivers
  31. 34. LUN <ul><li>A LUN refers to the individual piece in the storage system that is being accessed. Each disk in an array, for example, has a LUN. Disk partitions may also be assigned a LUN </li></ul>
  32. 35. Data Protection <ul><li>Backup Strategy </li></ul><ul><li>Recovery Method </li></ul><ul><li>ILM / HSM </li></ul><ul><li>DRP / BCP </li></ul>
  33. 36. Some terminologies <ul><li>Recovery Time Objective: (RTO) The amount of time that it takes to get your systems back online. </li></ul><ul><li>Recovery Point Objective: (RPO)This is the last consistent data transaction prior to the disaster. If you had a disaster, how much data would be lost? </li></ul><ul><li>The Disaster Recovery plan (DR) focuses on getting your business back up and running after a major outage </li></ul><ul><li>The Business Continuance plan (BCP) focuses on keeping your business running DURING the disaster. </li></ul>
  34. 37. Replication <ul><li>Asynchronized : </li></ul><ul><li>Does not affect application performance </li></ul><ul><li>Bandwidth determines how up to date your data stays </li></ul><ul><li>Database is consistent if solution uses sequencing </li></ul><ul><li>Great long distance solution </li></ul><ul><li>Site failure – transactions are rolled back or rolled forward </li></ul><ul><li>Synchronized : </li></ul><ul><li>Low or no transaction Loss </li></ul><ul><li>Database is always consistent </li></ul><ul><li>Site failure - same application recovery as power failure </li></ul><ul><li>Bad for long distance, affects application performance, requires massive pipes </li></ul>Snapshots: Instant data copy (Software based/Hardware based) Data Replication: Sync, Async, Bulk Copy/Adaptive Data Replication Method: Hardware, Software
  35. 38. Some Popular Replication Tools <ul><li>EMC Clariion Snap View – Local </li></ul><ul><ul><ul><ul><ul><li> Mirror View – Remote </li></ul></ul></ul></ul></ul><ul><li>EMC Symmetrix Time Finder – Local </li></ul><ul><ul><ul><ul><ul><li>SRDF - Remote </li></ul></ul></ul></ul></ul><ul><li>IBM Total Storage Flash Copy – Local </li></ul><ul><ul><ul><ul><ul><li>Volume Copy </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>PPRC - Remote </li></ul></ul></ul></ul></ul><ul><li>Hitachi Data Systems True Copy </li></ul>
  36. 39. <ul><li>SAN Security </li></ul>
  37. 40. Security - Controlling Access to the SAN <ul><li>Physical layout </li></ul><ul><ul><li>Foundation of a secure network </li></ul></ul><ul><li>Location planning </li></ul><ul><ul><li>Location of H/W and S/W components </li></ul></ul><ul><ul><li>Identify Data Center components </li></ul></ul><ul><ul><li>Data Center location for management applications </li></ul></ul><ul><ul><li>Disaster Planning </li></ul></ul>
  38. 41. Fabric Security - Zoning <ul><li>Zone </li></ul><ul><ul><li>Controlled at the switch layer </li></ul></ul><ul><ul><li>List of nodes that are made aware of each other </li></ul></ul><ul><ul><li>A port or a node can be members of multiple zones </li></ul></ul><ul><li>Zone Set </li></ul><ul><ul><li>A collection of zones </li></ul></ul><ul><ul><li>Also called zone config </li></ul></ul><ul><li>Single HBA Zoning </li></ul><ul><ul><li>A separate zone for each HBA </li></ul></ul><ul><ul><li>Makes zone management easier when replacing HBAs </li></ul></ul><ul><li>Types of zones: </li></ul><ul><ul><li>Port Zoning (Hard Zoning) </li></ul></ul><ul><ul><ul><li>Port-to-Port traffic </li></ul></ul></ul><ul><ul><ul><li>Ports can be members of more than one zone </li></ul></ul></ul><ul><ul><ul><li>Each HBA only “sees” the ports in the same zone </li></ul></ul></ul><ul><ul><ul><li>If a cable is moved to a different port, zone has to be modified </li></ul></ul></ul><ul><ul><li>WWN based Zoning (Soft Zoning) </li></ul></ul><ul><ul><ul><li>Access is controlled using WWN </li></ul></ul></ul><ul><ul><ul><li>WWNs defined as part of a zone “see” each other regardless of the switch port they are plugged into </li></ul></ul></ul><ul><ul><ul><li>HBA replacement requires the zone to be modified </li></ul></ul></ul><ul><ul><li>Hybrid zones (Mixed Zoning) </li></ul></ul><ul><ul><ul><li>Contain ports and WWNs </li></ul></ul></ul>
  39. 42. Zoning - Hard vs. Soft Zoning <ul><ul><li>Flexibility </li></ul></ul><ul><ul><li>Reconfiguration </li></ul></ul><ul><ul><li>Troubleshooting </li></ul></ul>Port Zoning WWPN Zoning <ul><ul><li>More Secure </li></ul></ul><ul><ul><li>Simplified HBA replacement </li></ul></ul><ul><li> </li></ul><ul><ul><li>Reconfiguration </li></ul></ul><ul><ul><li>“ Spoofing” </li></ul></ul><ul><ul><li>HBA replacement </li></ul></ul>Advantages Disadvantages
  40. 43. Fabric Security - Vendor Specific Access Control <ul><li>Most vendors have proprietary access control mechanisms </li></ul><ul><li>These mechanisms are not governed by the Fibre Channel standard </li></ul><ul><li>Examples of vendor features: </li></ul><ul><ul><li>McDATA </li></ul></ul><ul><ul><ul><li>Port Binding </li></ul></ul></ul><ul><ul><ul><li>SANtegrity </li></ul></ul></ul><ul><ul><li>Brocade </li></ul></ul><ul><ul><ul><li>Secure FabricOS </li></ul></ul></ul>
  41. 44. Security: Volume Access Control (LUN Masking) <ul><li>Restricts volume access to specific hosts and/or host clusters </li></ul><ul><li>Policies set based on functions performed by the host </li></ul><ul><li>Servers can only access volumes that they are permitted to access </li></ul><ul><li>Access controlled in the Storage Array - not in the fabric </li></ul><ul><ul><li>Makes distributed administration secure </li></ul></ul><ul><li>Tools to manage masking </li></ul><ul><ul><li>GUI </li></ul></ul><ul><ul><li>Command Line </li></ul></ul>
  42. 45. Backup <ul><li>Backup is the process of saving your data so that it can be restored in case of problems such as system failure or data corruption. </li></ul><ul><li>Backup Window: Time </li></ul><ul><li>Backup Policy: Full, Incremental, Differential </li></ul><ul><li>Backup Rotation: Daily, Weekly, Monthly </li></ul><ul><li>Backup Method: Network, SAN, Disk to tape, Disk to Disk, </li></ul>
  43. 46. Individual Backup Centralized Backup on LAN Disk to Disk Backup Tiered Backup
  44. 47. Some Popular Backup Softwares <ul><li>Veritas Netbackup </li></ul><ul><li>IBM Tivoli Storage </li></ul><ul><li>EMC Legato Networker </li></ul><ul><li>HP OmniBack </li></ul><ul><li>Veritas BackupExec </li></ul><ul><li>CA Brighstor Arcserve </li></ul>
  45. 48. Common storage terms <ul><li>CIFS – Common Internet File System – A NAS protocol </li></ul><ul><li>DAS – Direct-attached storage </li></ul><ul><li>FCIP - SCSI over FC tunneled through IP </li></ul><ul><li>HBA – Host bus adapter </li></ul><ul><li>iFCP - SCSI over FC translated to IP </li></ul><ul><li>iSCSI - SCSI over IP (often over Ethernet) </li></ul><ul><li>JBOD – Just a bunch of disks </li></ul><ul><li>LAN - Local area network </li></ul><ul><li>LUN - Logical unit number – The basic unit of block storage </li></ul><ul><li>MTBF - Mean time between failures </li></ul><ul><li>MTTF - Mean time to failure </li></ul><ul><li>NAS – Network attached storage </li></ul><ul><li>NFS – Network File System – A NAS protocol </li></ul><ul><li>RAID – Redundant array of independent disks </li></ul><ul><li>SAN - Storage area network </li></ul><ul><li>SCSI – Small Computer Systems Interface </li></ul>