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Cloning the Smart way with the SAN/iQ® SmartClone Feature
by Mike Moroze (republished with permission)
Have you ever made a copy of a copy and had that second copy not turn out so well? (Think Multiplicity here – the classic 1996 movie
starring Michael Keaton.) The good news with today's SAN/iQ software is that you can "make a copy or a copy of a copy" and have the data
be exactly the same as the original – saving you space in your SAN network and providing you with all the benefits of a SAN/iQ volume.
Let's dig a bit deeper into the SAN/iQ SmartClone feature.
In SAN/iQ, a SmartClone volume is simply a "copy" of the data. However, in this case the copy simply uses a bottom-level snapshot as its
base data store. Using the SmartClone feature creates a "top-level" volume (or set of volumes) that "sit" on top of the bottom level snapshot.
No space is wasted as there is only one copy of the bottom level snapshot (this snapshot is called a clone point in SAN/iQ terminology) for
all of the volumes created. No time is wasted as you have instant access to the data as the volume is created instantaneously. And it's simple
– you can create up to 25 new volumes at a time using the SmartClone feature. Let's take a quick look how volumes are created using the
First, find the volume from which you want to create new volumes in you SAN. There are several ways to access the SmartClone feature, but,
perhaps, the easiest is to right click on the volume of interest and select the New SmartClone… menu item. This brings up the dialog you see
Typically, snapshots are the "foundation" data store for SmartClone-created volumes, so if you start the process from a volume, you'll need
to create a snapshot of the volume before the new SmartClone volumes can be created. This snapshot, the clone point (for the point from which
all the "clones" were made), will serve as the bottom-level snapshot for the new volumes.
Once the snapshot has been created, you can simply click OK at this point to create a single volume. But the power here is to create multiple
volumes at once. You can do this by increasing the number of volumes (up to 25). Then click Update Table. At this point a default name of
the new volumes is entered in the table – the default is based on the snapshot name and your preference settings. You can then change the
various properties of the individual volumes by making the changes in the table. Another way to make the property changes is to change them
in the section of the dialog right above the table and click Update Table. This method changes the properties for all the volumes in the
table. Again, you can go in and make any single changes to the properties you need in the table itself.
Now, once you click OK, you'll instantaneously have 25 new volumes (or whatever number you selected). All of these volumes will "point to"
the single snapshot (remember, clone point) that was created (or used) as the base snapshot – no duplication of data here. Now you can write
new data to the volume that was just created. The only difference between volumes created "normally " and volumes created using the SmartClone
feature is that you can't delete the snapshot that is being used as the base snapshot – i.e., you can't delete the clone point – as long as
there are multiple volumes attached to it.
The Centralized Management Console has some new views that help you to understand the logical view of your volumes – this is especially helpful
when you are looking at volumes created by using the SmartClone feature. Select the clone point and then the tab labeled Map View. The Map
View allows you to look at the logical connections of all the shared volumes. Also, if you select a volume that was created by using the
SmartClone technology on the left-hand side, in the navigation tree, you'll see a highlight connecting all the volumes that share the clone
point. Drilling down, if you select the clone point, you'll see the highlight that shows all the shared volumes. While only one clone point
truly exists (and only one copy of the data), it's easier to understand all the relationships if the clone point is displayed with its related
volume in the navigation tree. (See below)
Cool stuff, right? But right now you may be asking yourself, what exactly do I need this for? And that's a good question. Since these are
space-efficient, thin-provisioned volume clones; they can help maximize your storage ROI. You can also use this feature to turn any snapshot
or volume into a full, permanent read-write volume on your SAN. You can use this feature to help you develop, test, and deploy new operating
system versions and applications. You can use the SmartClone feature to boot from SAN or implement a virtual desktop infrastructure. Only
your imagination limits the ways you can put SmartClones to work for you.
Blue Net note: This also can be a very efficient way to clone Citrix XenApp/Presentation Servers. Very efficient, and you get the benefit
of more efficient caching for better IOPs, and less load on your storage!