Thursday, September 19, 2013

INTERVIEW


Vault drives:
  • 1st 4 or 5 drives 
  • It contains 
    • Vault area, 
    • PSM Lun, 
    • Flare database Lun 
    • and Operating System. 
  • The Vault:
    • The vault is a ‘save area’ across the first five disks
    • to store write cache from the Storage Processors when power failure
  • The PSM Lun:
    • The Persistent Storage Manager Lun
    • stores the configuration of the Clariion
    • Such as Disks, Raid Groups, Luns, Access Logix information, SnapView configuration, MirrorView and SanCopy configuration as well.
  • Operating System:
    • The Operating System of the Storage Processors is stored to the first five drives of the Clariion.
Reserved LUN Pool
  • RLP works with Replication software
  • while replication stores the data/information required to complete a replication
  • RLP contains one or more Private LUNS.
Private LUN
  • The LUN become Private LUN, when it is added to RLP
  • These LUNs cannot belong to any storage group & a server cannot perform I/O to them.

Sunday, September 15, 2013

VNX SNAPSHOTS


  • VNX snapshots is a feature in VNX for Block OE release 32.
    • created to improve the existing Snapview snapshot 
      • by better integrating with pools
      • vnx snapshots can only be used with pool luns
      • bcz this technology require pool space
      • VNX snapview &Snapview Snapshots can coexist on the same pool LUN
  • Classic LUNs, LUNs that are created on physical RAID groups.
    • support only Snapview Snapshots.
  • VNX snapshots support 256 writable snaps per pool LUN.
    • support branching, also called Snap of Snap
    • a snap of snap hierarchy cannot exist 10 levels
    • no restriction on no.of branching
    • limit is 256 which is the hard limit
  • consistency groups are also supported with the feature.
    • several pool LUNs can be combined into a consistency group and snapped cocurrently.
HOW snapshots work
  • VNX snapshots use Redirect On Write(ROW) technology.
  • ROW redirects new writes destined for the primary LUN to a new location in the storage pool.
    • which is different from Copy On First Write(COFW) used in Snapview
Diffrence
  • VNX snapshots technology writes the new data to a new area within a pool as show in bellow figure
    • without the need to read/write to the old data block.
    • this improve overall performance compared to snapview
  • Similarly, during a read from a snapshot all data read from source lun
    • ths snapshot's data is not constructed from 2 different places
VNX snapshots point at unchanged blocks, primary lun is using new blocks for new i/o writes 

Snapshot granularity
  • Every VNX snapshot has 8KB block granularity.
    • i.e that every write occupies at least 8kb on the pool

Monday, August 26, 2013

ZONNIG


·         Identify the nodes on initiator & targets which are to be zoned.
·         Log in to FC switch
·         Check nodes were login in the FC switch or not
o   Get the WWN number from initiator by using host agent software or using fcshow  on cmd
o    To get the target WWN, On target gui management software Unisphere, go to settings ->
o   Check these both WWN numbers on FC switch by using command Switchshow
o   Also use another command nodefind [wwn no.]
·         Then create meaning full alias names for WWN of both initiator & target.
o   Observe alias names if already there on nodefind command.
o   If there are, no need to create new one.
o   To create new alias name use the command alicreate alias_name wwn
o   To show all alias names use the command alishow
o   To remove alias names use the command aliremove
·         Create the required number of zones
o   Syntax is
o   zonecreate “zone_name”,”alias_name_of_initiator;alias_name_of_target”
o   Give the easily identifiable zone name
o   Double quotes, camas and semi colans are must
o   To see the created zones use zoneshow
·         Then add these zones to active configuration file
o   To know the active configuration file use cfgactiv
o   Adding to zones active/normal config file cfgadd “cfg_file_name”,”zone1;zone2;etc”
·         Then save this configuration using cfgsave
·         Then enable the active configuration file(which is zone added on previous) using command cfgenable “config_filename”
·         Removing zones from any config files cfgremove “cfg_file_name”,”zone_name”
·         Delete zones zonedelete “zone_1”
·         Delete alias alidelete “alias_name”
Zone Status:
·         If successfully zoned between nodes of initiator and target
o   We can find the wwn numbers of host on the “connectivity status” window
§  Main menu -> Hosts -> connectivity status
o   If any host agent is installed on the initiator, we will find Initiator’s “Host Name” on the connectivity status
Terminology:

Host: server; target: storage; 

Thursday, August 22, 2013

Data Center


  • It is a facility that contain storage, compute, network, and other IT resources to provide centralized data-processing capabilities.
  • Core elements of data center work together to address data-processing requirements
    • Application: program provides logic for computing operations
    • DBMS: provides a structured way to store data in logical order
    • Host or compute: computing platform that runs appliations and database
    • network: data path gives communication among various network devices
    • storage: that stores data for subsequent use
  • Key Characteristics of Data Centre:
    • Avilability
    • Security
    • Scalability
    • Performance
    • Data integrity: Data integrity refers to mechanisms, such as error correction codes or parity bits, which ensure that data is stored and retrieved exactly as it was received.
    • Capacity: when capacity requirement increase, dc must provide additional capacity of resources.
    • manageability: A data center should provide easy and integrated management of all its elements. Manageability can be achieved through automation and reduction of human (manual) intervention in common tasks.
  • Managing Data Center:
  • Data is a collection of raw facts 
  • from which conclusions may be drawn and information is the intelligence and knowledge 
  • derived from data. Businesses analyze raw data to identify meaningful trends. On the basis of 
  • these trends, a company can plan or modify its strategy. 
  • Data can be classified as structured and unstructured. Big data refers to data sets whose sizes 
  • are beyond the ability of commonly used software tools to capture, store, manage, and 
  • process within acceptable time limits.
  • Information-centric architecture is commonly deployed in today’s data center. It helps to 
  • overcome the challenges of server-centric storage architecture.
  • A data center has five core elements such as application, database management system 
  • (DBMS), host, network, and storage. 
  • The key characteristics of data are availability, security, scalability, performance, data 
  • integrity, capacity, and manageability. 
  • Virtualization is a technique of abstracting physical resources, such as compute, storage, and 
  • network, and making them appear as logical resources. 
  • Cloud computing enables individuals or businesses to use IT resources as a service over the 
  • network.

Information data


  • Data is a collection of raw facts from which conclusions may be drawn.
  • data can be generated using a computer and stored in strings of 0s and 1s is digital data
    • access by user only after it is processed by a computer
  • Information is the knowledge derived from data.
  • 2 types of data(on how data is stored & managed):
    • structured(organized in rows & columns in a defined format, stored using DBMS)
    • unstructured if its elements cannot be stored in rows & columns(more % in total data).
  • Big data: data sets whose sizes are beyond the ability of commonly used software tools
    • to capture, store, manage, and process within acceptable time limits
    • it includes both structured & unstructured data
    • contains all types of data.

    Storage

    • Stores data created by individuals & organizations for further processing


    Evolution Of Storage Architecture:

  • The proliferation of departmental servers in an enterprise resulted in unprotected, unmanaged, fragmented islands of information and increased capital and operating expenses.
  • To overcome these challenges, storage evolved from server-centric to information-centric architecture. In this architecture, storage devices are managed centrally and independent of servers. These centrally-managed storage devices are shared with multiple servers. When a new server is deployed in the environment, storage is assigned from the same shared storage devices to that server.