Monday, February 21, 2011

Easy Tier Manual Mode without SSD drives ? No way !

Update : this post has become obsolete.
I'm not deleting it because the comments contain valuable information.
Check out my update : Easy Tier Manual Mode without SSD drives ? Yes you can !

I'm not exactly sure how I should begin this post. I might say something like : I must apologize to all our customers to whom I explained Easy Tier for not telling the truth. Or perhaps : damn, I hate some of those IBM announcements for only telling half of the story. Mind you, there are no lies in these announcements, but they're not telling everything, they leave out things and people tend to try and fill in the blanks for themselves. That's exactly what I did with Easy Tier on DS8000.

You know there's an Automatic and a Manual mode. Well, for the Automatic mode you need to have SSD drives. That's the whole point of using Easy Tier in automatic mode, making sure the most accessed data are put on the SSD drives.

But then, there's the Manual mode. What is it for ? I'll just quote what I wrote about it when it was first announced :
"Volume migration - Enables the manual relocation of volumes between extent pools, as well as the restriping of volumes within an extent pool, and the ability to merge existing extent pools".
You don't even have to have SSDs installed in order to use Easy Tier functionalities. The second feature operates at volume level. "Easy Tier also includes the ability to dynamically relocate individual logical volumes to another drive tier or to another drive type within a tier. For example, clients can move a volume from a set of 15,000 RPM spinning drives to a set of 10,000 RPM spinning drives. In addition, they can also change a volume’s RAID type from, say, RAID 5 to RAID 6, as well as change the way data is striped within the system. For instance, a volume that was configured to stripe data across a single RAID array can be changed to stripe data across multiple arrays for better performance. And all of this can be done dynamically without disrupting applications."
I put one specific sentence of mine in bold because it is absolutely NOT true. Even for Manual Mode you do have to have at least some SSD drives into your DS8000. This is the official answer I received from IBM TechLine. I really thought you didn't have to and no one has ever told me you did. This is what always bugs me : the announcement doesn't mention this SSD requirement, so you start thinking things, filling out the blanks. Well, you shouldn't. What isn't there, isn't there for a reason . . . And Easy Tier without SSD drives just isn't there.


Nick Clayton said...

It is possible to use the Easy Tier manual migration function without having SSD drives installed. You do however have to have requested the zero charge Easy Tier feature to do this. If you have any statement from the techline organisation then please could you forward this to me so I can ensure we provide more accurate information in future

Anonymous said...

I can tell you that I have used the manual mode method on a DS8700 with NO SSD and it worked just fine.
ALl you need are the R5.1 code level installed and the EasyTier license key(which is a $0 key).
Once both those things are true, manual mode (reblancing vols and merging extent pools) is possible regardless of whether SSD is present or not.