Allocate a lun – masking/mapping

Allocating a lun it's the process where you present a carved lun to a host or to more hosts (if you have a cluster for example).

You do need to know the LDEV id that you want to present and also you need to know what lun number that host will see your ldev. You can present luns in any order you want to a host by aligning different ldev id's to different host ldev numbers.

Allocate a lun

Just as with carving, there are quite a few places to use to allocate a lun.

    • While in resources view, Actions Menu, Allocate Volumes.alloclun1
    • From the Actions menu on the right hand side, click the little down arrow and select allocate volumes. alloclun2
    • At any given time select the Allocate Volumes from the lower menu on the left hand side under General Tasks.


Anyway this is the step-by-step instructions on how to add a volume in HDS

    1. First select your host that you will be assigning a lun. If you're host is not registered, you need to register it first.
      alloc_step1If you are presenting a lun to multiple hosts, you can do so in one step by pressing the little Select Hosts button on the left side.
      From the Select Hosts Screen, add the hosts you want to add then press the Add button followed by OK. If you don't see the hosts here, and you know your hosts are registered make sure the filter option is off.
    2. Select the storage system and volume type, then change the volume selection to manual (make sure Advanced Options is clicked if you don't see it) and press the add volumes button
    3. Once the add volumes wizard is on the screen, you need to select unallocated volumes (for newly carved volumes) or allocated volumes if you want to add a volume that is already presented to a host (new cluster requirement by example). Select the volume or volumes then click Add. Once done click OK. If you have to present multiple volumes where some are HDP volumes and some are HDT volumes you need
    4. Once this is done, if this is the first time this host has new storage from this array, you will need to tell the storage array what WWN is zoned to what port. Expand Lun Path Options and click the Edit Lun Paths button.
      Normally each server has two connectivity paths between the storage arrays and itself to insure redundancy. If one path goes down (cable problem, defective card, etc), the server won't lose it's disk as it can still see it on the other path. Each path is connected to a Target port on the array and it's defined by a WWN.
      In the Edit Lun Paths screen you are specifying how this server is connected. The server is already registered at this point into Device Manager so you will see it's WWN's on the right hand side. On the left side, you see all the target ports on the server. Scroll down until you find your port then click on it. It will appear on the left side of the picture. If you click on it you will be able to draw a line from the port to the wwn. Click on the wwn where that port is connected then repeat for the second port.
      Once done you will see a map representing your zoning (the blue lines) with Storage on the left side and server on the right side.Make sure you get the paths properly, too many times, storage admins are not careful here and don't do the mapping correct. If WWN 11:11:11:11:11:11:11:11 is connected to CL1-A and WWN 22:22:22:22:22:22:22:22 is connected to CL2-A, this is how the screen should look as well. One line between 11:11....:11:11 and CL1-A and the other line between 22:22:...:22 and CL2-A.
    5. Next you need to specify your host group options. Scroll down in the Allocate Volumes screen until you see a button called Host Group and LUN settings
      These are optimizations made by Hitachi to get the max of stability and performance from your array. Try to match your Host mode with your OS. The difference between Windows and Windows Extension is that Windows Extension groups are allowed to have luns expanded, where Windows Hosts don't.
    6. Last step is to specify the lun order. This is the order that the host will see the volumes allocated. If you use auto, the system will use the next available number. If you use manual then click the Select LU Number and in the Select LU Number screen match the volume the a particular volume number. Note that some host types want volume 0 reserved for bootfromsan and other o/s don't see volumes over 255.addlunorder
    7. Click the show plan button and review the config. Double check the LUN number is the same for all the hosts and that the WWN's are aligned properly to their appropriate ports. When ready hit Submit
    8. Click on Tasks&Alerts and watch for succesfull completion of your task.

Once finished let the admin know the ldev id's you've assigned for him

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