Data is migrated. What would be the advantage of migrating only the pointers to a faster layer ?

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The unit of thin pool allocation is an extent which is 12 tracks or 768Kbytes. The extents are striped across all members of the pool.

Also to understand what "Extents" mean in Virtual Provisioning context , please see the following doc :

https://support.emc.com/docu7383_Best-Practices-for-Fast,-Simple,-Capacity-Allocation-with-EMC-Symmetrix-Virtual-Provisioning.pdf

Hi,

Please see the following document to get a better understanding on FAST. Its got the diagrams you seek :

https://support.emc.com/docu9286_Implementing-Fully-Automated-Storage-Tiering-(FAST)-for-EMC-Symmetrix-VMAX-Series-Arrays-Technical-Note.pdf

Thanks

Arjun

i am not clear still. if you have diagrammatic explanation it would be helpful for me.

actually is the data getting copied or not  in FAST VP migrations  ?

or is data device is getting migrating ?

i know thin device is not migrating because its a cache only entity.

Thin devices point to 768K extents in a thin pool (data devices).  FAST VP moves extents on the data devices, and changes the pointers on the thin devices to point to where the data has been moved to.

hello arjun,

i could understand the fast concepts. but  just want to know  what does extends means. because its really a good thing to know. this is the main difference between  FAST VP and FAST DP.

only extends are copied to other pool in VP. but in DP it copies the whole Devices.

the link which you gave for extend is not working . please provide me some other link and help me

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If you move the whole device (VLUN) from one pool to another, like in this example from SATA pool to FC pool, you will change all the TDEV pointers to point to where the data was moved to, the FC pool, and you will get FC performance.

For FAST DP there is no VP provisioning, or TDEVs or pointers to extents in a data pool.

Hi quincy,

thanks for the reply. Yes, so it moves only the extends in VP migration. that is 768 K only.

So next doubt regarding this is, If i want to migrate from Sata pool to Fibre Pool , at this time only extends are getting copied to Fibre pool data devices. so what would be performance character while moving this. whether it gives SATA pool performance or Fibre Pool performance.