SAN/NAS & networking basics

  1. Define NAS
    • NAS (Network attached storage) - Computer connected to a network that only provides file-based data storage services.  Ex:  freenas
  2. • List some protocols that use NAS
    • Protocols used: NFS (for UNIX), CIFS/SMB (for windows), AFP ( for mac)
  3. • What is the difference between NAS & DAS
    • The difference between NAS & DAS (Direct-attached storage) is that DAS is an extension to an existing server, not networked

    • NAS can have better performance than DAS over network.

    • Provides both storage and filesystem, appears as server on network to other computers

    • Can enable simpler and lower cost systems such
    • as load balancing and fault-tolerant email & web services
  4. • What is AFP?
    • AFP (apple filing protocol) – TCP port 548o Afp 3.0 introduced in mac os server 10.0.3o AFP 3.1 – Mac os x server 10.2o Afp 3.2 – mac os x server 10.4 – added ACLs (access control lists)
  5. • What is a SAN (Storage area network)
    • Provides access to consolidated, block level data storage.  Used to make storage devices, such as disk arrays, tape libraries, and optical juke boxes, accessible to servers so devices appear like locally attached devices to the OS.
  6. • What is a LUN
    • LUN (Logical Unit Number) – used to identify logical unit, which is a device addressed by SCSI.  Used to refer to a logical disk on a SAN.

    • Multiple systems cannot share a LUN, they would interfere with each other and corrupt data.  Any planned sharing of data on different computer requires SAN file system or clustered computing.
  7. • Name a few SAN protocols
    • SAN Protocols:  AoE, FCP, FCoE, FICON, HyperSCSI, iFCP, SANoIP, iSCSI, iSER
  8. • List FCP’s topologies
    • Fiber Channel has 3 topologies:

    1. Point-to-point (fc-P2P) – 2 devices are connected directly to each other. Simplest topology, limited connectivity. Dedicated bandwidth. Uses N_port (node port).

    • 2. Arbitrated Loop (FC-AL) – Devices are connected in a one-way loop fashion in ring topology.
    • • Serial architecture, compatible with scsi, handles up to 127 ports (devies).
    • • Bandwidth is shared among all ports
    • • Only 2 ports may communicate at a time.
    • • Arbitrated loop with only 2 ports is valid, even though it has the same topology as point to point, it still acts as loop protocol.
    • • Ports capable of arbitrated loop communication are NL_port (Node loop port) and FL_port (fabric loop port), collectively referred to as L_ports.
    • • Arbitrated loop with no fabric port (NL_ports) is called a private loop.
    • • Arbitrated loop connected to a fabric through FL_port is a public loop.
    • • Can be cabled in ring fashion or using hub. Physical ring stops working if one device fails, hub keeps working.
    • • Max speed: 8GFC

    • 3. Switched fabric (FC-SW) – All devices connected to fiber channel switches. Sometimes may be just called “fabric”.
    • • Up to 2^24 (16 million devices) can be connected.
    • • Most expensive topology
    • • Traffic between 2 ports flow through switches only, not transmitted to other ports.
    • • Failure of a port is isolated, does not affect other ports.
    • • Multiple pairs of ports may communicate simultaneously in a fabric.
    • • Visibility among nodes is typically controlled with zoning.
  9. What is NDMP
    NDMP (Network Data Management Protocol) is an open protocol used to control data backup and recovery communications between primary and secondary storage, originally created by NetApp.  by default, uses port 10,000

    NDMP minimizes demands on network resources and enables localized backups anddisaster recovery. With NDMP, heterogeneous network file servers can communicate directly to a network-attached tape device for backup or recovery operations. . Without NDMP, administrators must remotely mount the network-attached storage (NAS) volumes on their server and back up or restore the files to directly attached tape backup and tape library devices.
  10. List the commonly used port number & protocol for FTP, FTPdata, SSH, Telnet, SMTP, DNS, TFTP, HTTP, POP3, IMAP, HTTPS, NTP, & NDMP.
    • FTP - DATA - 20 - TCP
    • FTP - 21 - TCP
    • SSH - 22 - TCP
    • Telnet - 23 - TCP
    • SMTP - 25 - TCP
    • DNS - 53 - UDP/TCP
    • TFTP - 69 - UDP
    • HTTP - 80 - UDP /TCP
    • POP3 - 110 - TCP
    • NTP - 123 - TCP
    • IMAP - 143 - TCP
    • HTTPS - 443 - TCP
    • NDMP - 10,000 - TCP/UDP
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SAN/NAS & networking basics
SAN/NAS & networking basics