lun mapping and masking

Hello Tanislavm,

For your first question about the LUN mapping ID and Host id, @ Symmetrix series

Let say I am inside a closed room and I need / some one trying to contact me from outside world. I need a passage to be made to make the communication (same as the port concept on networking). Once the passage is made then I will have communication address to reach the correct destination.

The passage is my LUN ID which we used while mapping a symmetrix volume on the FA ports. The communication address is my Host ID for host (assume the server has 10 LUNs from the same storage). This is the value D on the CTD (Control, target & Device)

Correct me if I am wrong.

Regards,

Peri

The attached document is for the older CX3 series arrays but contains the basic information that applies to all the EMC arrays pertaining to host connections (see page 25) and the way zoning and masking works. Masking (Access Logix) is normally enabled by default on the newer arrays and when it is, that enables the use of Storage Groups. Storage groups allow you to put LUNs and hosts into a container (Storage Group) that will isolate those from other hosts - masked.

glen

Hi,

At the moment when a certain lun is assigned to a storage group,this could be assigned also to a new host which is not yet registered with that storage group?

tnx a lot,

marius

LUNs can only be assigned to hosts that are logged in, registered and in a Storage Group. When you create a LUN, you next would assign that LUN to a Storage Group that contained a host. LUNs can belong to multiple Storage Groups, meaning that more than one host can access that LUN, but the hosts would have to have clustering software. Hosts can only be assigned to one Storage Group.

glen

Hi Glen,

An host needs to login to have access to storage group,right?Every time when a host in booted up,it will log in the SAN,means it will log in OS from SAN to access a resource-storage group?

tnx a lot,

marius

If you have a host that has a local disk with the operating system, when that host boots from the local hard disk, during the start up, the disk manager of the operating system will initialize the host HBA's. If the HBA's are connected to a fiber channel switch and the switch has been correctly zoned so that the host HBA's will connect to the array SP ports, then the HBA will do a fiber channel login to the array. The array will see the host HBA's and based on whether or no this host has been previously logged in and registered on the array and assigned to a Storage Group and there are LUNs in that Storage Group, then the host will see the LUN's as disks. This is the normal way a host is connected to the array.

A different way but based on the same steps above is if the host does not have a local hard disk and is using a LUN on the array to boot from. This is called boot-from-SAN. This requires a different setup. You must create the operating system on a LUN, that LUN must be in a Storage Group and the HBA's must be set up to boot from this LUN.

There documents on the support.emc.com site called "Host Connectivity Guides" that provide step-by-step instructions for connecting a host to an array using both of the above methods. If the array that you're attempting to connect to is a Unified VNX, then you can find customer documentation at mydocs.emc.com.

glen

Hi,

If I change an faulty HBA in a server,then the corresponding 2 wwpn within this HBA will need to be erased from FC switch(zoning) and also from SAN(as initiators)?

tnx a lot,

marius

You would remove the old initiators from the storage group and add the new initiators. Make sure the new initiators are logged in and registered on the CX before you add them into the storage group

Correct. Update your host zone to include the new WWPN and make sure the new initiators are masked.

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glen

Hi,

I must to migrate EMC Clariion to VNX using host mirroring.

Fine.

If I am aware of the size of a LUN from Clariion then I should create the same size LUN in VNX?Or larger  size of LUN in VNX,whith how much larger(10% larger)?

If I am not aware of the size of LUN in Clariion,only aware of file system on an certain server,then what will be the size of the LUN in VNX to be created?Normally when I have a LUN and then I will create metadata on it and file system,there will be 10% loss of the initial LUN size?Thus knowing the size of an certain file system I should create the LUN size in VNX at last with 10% larger?

tnx a lot,

marius

Hey Ernes,

Initiators here meant as?

what is the difference between a initiator and a host?

A host contains HBA's Host Bus Adapter). Each HBA port has an address called the WWN and is an "Initiator" - the initiator establishes the connection from a host to an array (the target). Each initiator is a physical HBA port. Some HBA's have a single port, other HBA's may have two ports.

Here's a good link with the basics:

http://blog.osnexus.com/2012/03/20/understanding-fc-fabric-configuration-5-paragraphs/

glen

Thank Glen,

Been a great help!!!!!:)

Also, could you plz let me know, in which kind of environment, i can implement what all raid types Like if i have a database server, which Raid?

For oracle, Which raid? etc, just a brief idea!!!