EMC Storage Product Knowledge Sharing

I have been receiving mail to write on basic storage topic rather than only EMC. Here is first basic thing to know about FC technology.

Fibare Channel is nothing but just a medium to connect host and shared storage. When we talk about SAN first things comes in mind about Fibre Channel.

Fibre Channel is serial data transfer interface intended for connecting shared storage to computer. Where storage is not connected physically to host.

Why FC is most important in SAN? Because FC gives you high speed through the following process:

1) Networking and I/O Protocol such as SCSI command, are mapped to FC construct
2) Encapsulate and transported with FC frame.
3) With this, the hight speed transfer of multiple protocol is possible over same physical interface.

FC operate over copper wire or optical fibre at the rate upto 4GB/s and upto 10GB/s when used as ISL (E - Port) on supported switch. At the same time, latency is kept very low, minimizing the delay between data requests and deliveries. For example, the latency across a typical FC switch is only a few microseconds. It is this combination of high speed and low latency that makes FC an ideal choice for time-sensitive or transactional processing environments.

These attributes also support high scalability, allowing more storage systems and servers to be interconnected.Fibre Channel is also supports a variety of topologies, and is able to operate between two devices in a simple point-to-point mode, in an economical arbitrated loop to connect up to 126 devices, or (most commonly) in a powerful switched fabric providing simultaneous full-speed connections for many thousands of devices. Topologies and cable types can easily be mixed in the same SAN.

FC is the most important in building SAN, it gives us flexibility to use protocol like FCP, FICON, IP (iSCSI, FCIP, iFCP) and uses block type data transfer.

if we want to define what is FC - Fibre Channel is a storage area networking technology designed to interconnect hosts and shared storage systems within the enterprise. It's a high-performance, high-cost technology. iSCSI is an IP-based storage networking standard that has been touted for the wide range of choices it offers in both performance and price.

Fibre Channel technology is a block-based networking approach based on ANSI standard X3.230-1994 (ISO 14165-1). It specifies the interconnections and signaling needed to establish a network "fabric" between servers, switches and storage subsystems such as disk arrays or tape libraries. FC can carry virtually any kind of traffic.

However, there are some recognized disadvantages to FC. Fibre Channel has been widely criticized for its expense and complexity. A specialized HBA card is needed for each server. Each HBA must then connect to corresponding port on a Fibre Channel Switch. creating the SAN "fabric." Every combination of HBA and switch port can cost thousands of dollars for the storage organization. This is the primary reason why many organizations connect only large, high-end storage systems to their SAN. Once LUNs are created in storage, they must be zoned and masked to ensure that they are only accessible to the proper servers or applications; often an onerous and error-prone procedure. These processes add complexity and costly management overhead to Fibre Channel SANs.

When running inq or syminq, you'll see a column titled Ser Num. This column has quite a bit of information hiding in it.

An example syminq output is below. Your output will differ slightly as I'm creating a table from a book to show this; I don't currently have access to a system where I can get the actual output just yet.

Using the first and last serial numbers as examples, the serial number is broken out as follows:

So, the first example, device 009 is mapped to director 15, processor A, port 0 while the second example has device 01A mapped to director 12, processor B, port 0.

SYMCLI BASE Commands

symapierr - Used to translate SYMAPI error code numbers into SYMAPI error messages.
symaudit - List records from a symmetrix audit log file.
symbcv - Perform BCV support operations on Symmetrix BCV devices.
symcfg - Discover or display Symmetrix configuration information. Refresh the
host's Symmetrix database file or remove Symmetrix info from the file. Can also
be used to view or release a 'hanging' Symmetrix exclusive lock.
symchg - Monitor changes to Symmetrix devices or to logical objects stored on Symmetrix
devices.
symcli - Provides the version number and a brief description of the commands included in
the Symmetrix Command Line
symdev - Perform operations on a device given the device's Symmetrix name. Can also be
used to view Symmetrix device locks.
symdg - Perform operations on a device group (dg).
symdisk - Display information about the disks within a Symmetrix.
symdrv - List DRV devices on a Symmetrix.
symevent - Monitor or inspect the history of events within a Symmetri
symgate - Perform operations on a gatekeeper device.
symhost - Display host configuration information and performance statistics.
syminq - Issues a SCSI Inquiry command on one or all devices. Interface.
symlabel - Perform label support operations on a Symmetrix device.
symld - Perform operations on a device in a device group (dg).
symlmf - Registers SYMAPI license keys.
sympd - Perform operations on a device given the device's physical name.
symstat - Display statistics information about a Symmetrix, a Director, a device group, or a
device.
symreturn - Used for supplying return codes in pre-action and post-action script files.

SYMCLI CONTROL Commands

symacl - Administer symmetrix access control information.
symauth - Administer symmetrix user authorization information.
symcg - Perform operations on an composite group (cg).
symchksum - Administer checksum checks when an Oracle database writes
data files on Symmetrix devices.
symclone - Perform Clone control operations on a device group or on a
device within the device group.
symconfigure - Perform modifications on the Symmetrix configuration.
symconnect - Setup or Modify Symmetrix Connection Security functionalit
symmask - Setup or Modify Symmetrix Device Masking functionality.
symmaskdb - Backup, Restore, Initialize or Show the contents of
the device masking database.
symmir - Perform BCV control operations on a device group or on a
device within the device group.
symoptmz - Perform Symmetrix Optimizer control operations.
symqos - Perform Quality of Service operations on Symmetrix Devices
symrdf - Perform RDF control operations on a device group or on a
device within the device group.
symreplicate - Perform automated, consistent replication of data given
a pre-configured SRDF/Timefinder setup.
symsnap - Perform Symmetrix Snap control operations on a device
group or on devices in a device file.
symstar - Perform SRDF STAR management operations.
symrcopy - Perform Symmetrix Rcopy control operations on devices in
a device file.

SYMCLI SRM(Mapping) Commands

symhostfs - Display information about a host File, Directory,
or host File System.
symioctl - Send IO control commands to a specified application.
symlv - Display information about a volume in Logical Volume
Group (vg).
sympart - Display partition information about a host device.
symrdb - Display information about a third-party Relational
Database.
symrslv - Display detailed Logical to Physical mapping information
about a logical object stored on Symmetrix devices.
symvg - Display information about a Logical Volume Group (vg).