Radosalw,

 
> Yes, it depends. It can depend on things you described, but also on the
detail
> level. Usually you can map logical volume to the dasd array ;-) but
sometimes
> it you can go down into details liek raid group.

[Ron Hawkins] Mapping a HDP pool is a bit like mapping a log structured
file. For IBM you may be able to map their wide striped pools because the
stripe chunk is 2GB in size, but for HDS using 38MB chunks, and I think EMC
use 7Mb chunks you will not be able to map the a volume to an array group.
This is not a problem though, as your monitoring and tuning become more
focused on pool of array groups, rather than discrete array groups.

> 
> Agreed. Although you didn't mention redirected "bad" sectors ;-)
> 
[Ron Hawkins] That's why you encrypt at installation. :-)

> 
> Encryption is a matter of time and cost. The question is WHEN I will
decrypt
> the data, not IF. And WHEN depends on my budget (the more money the
> more zombies works for me) and piece of good luck (I can guess the key 5
> min. after start or as last possible value).
> 
[Ron Hawkins] I'm not sure I follow the point. Encryption occurs when the
data is destaged to the array group, and decrypted when you read it from the
disk. There's no overhead to this . If you mean switching encryption on for
existing array groups then yes there will be some planning involved.

> So the only sure way is still flame of Mordor. ;-)
[Ron Hawkins] Or the vendor's secure erase utility built into the
controller.

Ron

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