EVA Continuous access

[galenr4]

Gentlemen/Madams- A question... Since the EVA stripes across all avilable disks there are no selected "raid groups" per se.How then does one determine exactly where that data is and how is it kept uncorrupted/in tact and synchronized during datatransfer during CA operations? I wouldn't know the block count to ensure my DR disk is the correct size to copy to if I don't know where the data is precisely. I hope you can visualize what I a,m saying here and trying to undeerstand the mechanism... Any insight is greatly appreciated. Thanx in advance

[Uwe Zessin · Accepted solution]

You can't determine on which disk drive which data block is stored. Even if you had found it out, it can change over time.

> how is it kept uncorrupted/in tact

By properly keeping track of the internal meta data.

> synchronized during datatransfer during CA operations?

That is a function of the controller firmware - if it does not - that would be a bug in the software.

> I wouldn't know the block count to ensure my DR disk is the correct size to copy to if I don't know where the data is precisely.

Sorry, I don't understand - the EVA firmware makes sure that the destination virtual disk has the same size like the source disk. In fact, it creates the destination virtual disk for you when you set up a copy-set.

[galenr4]

Thank you much Uwe.

That clears many things up for me. So the firmware handles most of the operations. If its not to much to ask, might you expand on "properly keeping track of the internal meta-data"... just a brief note would suffice...is there a tool,script, or section in the GUI I should familiarize myself with ?

[Uwe Zessin]

> might you expand on "properly keeping track of the internal meta-data"

What I meant is: the integrity of the user data is ensured by not making programming errors in the controller firmware.


If you will be responsible for managing / implementing CA EVA, I suggest you make yourself familiar with:
- Command View EVA - the main management GUI
- SSSU (Storage System Scripting Utility)
-- for simple automation tasks
- RSM (Replication Solutions Manager)
-- a framework for Business Copy and Continuous Access management tasks

[galenr4]

GOTCHA... THANX AGAIN...downloading docs now !!!

Much Obliged