Usr, Snapshot and Adm Space

[kisalipa]

Hi Friends,

I am new to understanding HP 3PAR 10400 and 10800 models we have in our environment.

While trying to understand CPG's, I am not getting what exactly is the ADM space and the exact differences between Snapshot and Usr space. Can someone please give explanation with some example?

I have gone through some docs but not able to figure out the exact meaning.

Thanks in Advance!!

[Dennis Handly]

Check out HPE 3PAR StoreServ Storage Concepts Guide:

http://h20564.www2.hpe.com/hpsc/doc/public/display?docId=c04204225

USR: Contains the data of the base VV

SNP: Contains the changes from the base VV and snapshots

ADM: Contains the metadata that describes what has changed (for snapshots)

[kisalipa]

Thanks Dennis for the reply. The ADM space always shows a 0 for FPVV. Any reason for that??

[Sheldon Smith]

For a Fully Provisioned Virtual Volume, there can be no metadata changes. The entire volume is already there! :)

[kisalipa]

Thanks Sheldon. So I understand metadata has the information of the actual data(indexes of files or user data) that is filling up the Virtual Volume or the CPG??

What I understood earlier was, if the metadata size or ADM size displayed as 512MB for a 500GB TPVV, I felt it is the increments of 512MB as the data fills up the physical capacity??

Please clarify the confusion.

[Sheldon Smith · Accepted solution]

Sorry, no. The metadata tracks the changes (growth) of a Thin volume, in 32 MB regions. The user data is in the Usr space (in 128 MB regions). A Fully provisioned volume has no growth, therefore no Adm spaec.

[kisalipa]

Thanks a lot Sheldon. Now its clear.

Can you please answer my another post - CPG Growth increments??