EMC VNX | David Ring//

For every Pool LUN regardless of whether the LUN is thick or thinly provisioned there are 3 owner types assigned to each LUN:

Allocation Owner
Default Owner
Current Owner

There has been cases where inconsistencies in Current, Default & Allocation LUN ownership results in poor performance. Please review the EMC KB88169 written by Dave Reed for more detail.

Jon Klaus goes into good detail on the topic in his post ‘VNX Storage Pool LUN Ownership’

All three owner types need to align with the same ‘VNX Storage Processor’ (A/B) for best performance. If all 3 owners are aligned correctly then there is no need for the system to redirect I/O across the CMI to a peer Storage Processor. This is an example of a best practice LUN ownership configuration as viewable from the LUN properties in Unisphere:

With VNX2 when you create multiple LUNs from Unisphere the ownership is evenly balanced between SP A/B, this results in a balanced LUN configration. With VNX1 you need to specify the owner under the advanced tab while creating the LUN(s) in Unisphere to keep the LUNs evenly balanced across Storage Processors, or you can create the LUNs using cli and specify the SP owner as follows:

naviseccli lun -create -type nonThin -poolName ‘PoolName’ -sp a -capacity 20 -sq gb -name ‘LunName_SPA’ -l 1

naviseccli lun -create -type nonThin -poolName ‘PoolName’ -sp b -capacity 20 -sq gb -name ‘LunName_SPB’ -l 2

To generate a report of all POOL LUN properties including Ownership values from Unisphere chose the system tab and click on the ‘Reports’ option:
From the next window chose the reports window and select Pool LUNs:
You will then be presented with a HTML report with details for each LUN:VNX_LUN_OWN4

You can also use the following Navicli command to generate a listing of all your LUNs Ownership values:
naviseccli -h SP_IP lun -list -alowner -default -owner

Example Output:
Name: LunName_SPA
Current Owner: SP A
Default Owner: SP A
Allocation Owner: SP A

Name: LunName_SPB
Current Owner: SP B
Default Owner: SP B
Allocation Owner: SP B

To lookup the ownership values on an individual LUN basis use the navicli command below or from Unisphere view the properties of the LUN (as per above):
naviseccli -h SP_IP lun -list -l 1 -alowner -default -owner
naviseccli -h SP_IP lun -list -l 2 -alowner -default -owner

Changing Ownership
Now we are going to look at how we can change the Pool LUN ownership types beginning with the Allocation owner. Changing the Allocation Owner is only recommended if you have an imbalance of SP LUN ownership in your system. The only way to achieve this (changing the Allocation Owner) is to create another LUN of equal characteristics but on the other Storage Processor and then migrate the source LUN to the newly created target LUN on the opposite SP as the following example demonstrates:

1. For example create a New pool LUN (target) to migrate the source LUN to:
naviseccli lun -create -type nonThin -poolName ‘PoolName’ -sp b -capacity 20 -sq gb -name ‘LunName_SPA’ -l 3

2. Migrate ‘LUN ID 1′ to the new LUN which now has an allocation owner of SP B (More on LUN migration HERE):
naviseccli -h SP_IP migrate -start -source 1 -dest 3 -rate asap

After the migration you can see that the Allocation Owner is now ‘SP B’ but the Current and Default Ownership’s remain with ‘SP A’:
naviseccli -h SP_IP lun -list -l 1 -alowner -default -owner

Current Owner: SP A
Default Owner: SP A
Allocation Owner: SP B

3. Changing the Default Owner using the LUN -modify command or change through the LUN properties window in Unisphere:
naviseccli -h SP_IP lun -modify -l 1 -sp B

4. To change the Current Owner you will need to execute a trespass command on the LUN using navicli or by right clicking on the LUN in Unisphere and click the trespass option:
naviseccli -h SP_IP trespass lun 1
If changing on multiple LUNs then running the trespass mine command from the SP will trespass all the LUNs that the SP has DEFAULT ownership of. For example to trespass LUNs with Default Ownership of ‘SP B’ but which are currently owned by ‘SP A’:
naviseccli -h SPB_IP trespass mine

After completing these 4 steps the LUN ID 1 now has Current and Default ownership to match the Allocation owner:
naviseccli -h SP_IP lun -list -l 1 -alowner -default -owner

Current Owner: SP B
Default Owner: SP B
Allocation Owner: SP B

Note: RAID Group LUNs do not have an allocation owner. With MCX Raid Group LUNs are truly symmetric active/active – Future enhancement for POOL based LUNs, until then please be aware of your LUN ownership values.


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