We continue listing the best practice from storage engineering:
15) Management – Storage is very much a resource. It can be created, update and deleted. With software defined technologies, the resource only takes a gigantic form otherwise it is the equivalent of a single data record for the user. Every such resource has also significant metadata. Consequently we use manage storage just the same way as we manage resources.
16) Monitoring – Virtual large storage may be stretched across disks in one form or the other. And the physical resources such as disks often have failures and run out of space. Therefore monitoring becomes a crucial aspect. 
17) Replication groups – Most storage organization have to deal with copies of the data. This is generally handled with replication. There is no such limit to the copies maintained but if it spans across root of storage organization, a replication group is created where these different sites are automatically sync’ed.
18) Storage organization – We referred to hierarchical organization earlier that allows maximum flexibility to the user in terms of folders and depth. Here the organization includes replication groups if any as well as ability to maintain simultaneous organization such as when the storage is file system enabled.
19) Background tasks – routine and periodic tasks can be delegated to the background workers instead of executing them in line with data in and out. These can be added to a background task scheduler that invokes them as specified.  Some of the metadata for the storage entities is improved with journaling and other such background operations.
20) Relays – Most interactions between components is in the form of requests and responses.  These may have traverse through multiple layers before they are authoritatively handled by the node and partition. Relays help translate requests and responses between layers. They are necessary for making the request processing logic modular and chained.

#codingexercise
to determine if an integer binary tree is binary search tree, we can simply check if the root and leaves are within int_min and int_max and then reverse for every child.
bool IsBstHelper(node root, int min, int max)
{
 if (root==null) return true;
 if (root.data < min || root.data> max) return false;
return IsBstHelper(root.left, min, root.data-1) &&
           IsBstHelper(root.right, root.data+1, max);
}