Originating Author: David Floyer
Thin provisioning is one of the few storage advances where the concept and benefits can be understood by a layperson in less than a minute. However, if thin provisioning is implemented just to solve over allocation of storage, the main potential value will not be realized. Oracle has shown how the integration of its 10g database software with virtual volumes, automated placement and thin provisioning can make systems simpler to setup, grow, and monitor. Oracle uses Auto Extend and its Automatic Storage Manager to utilize the advanced functionality of a storage controller to provide storage services. This type of approach should be a model for software and internal development.
In addition, users should note that clearly some software is not well-suited to thin provisioning. Microsoft's NTFS for example prefers new, unused blocks rather than reusing released blocks unless it is formatted the appropriate way. Moreover, certain other applications will grab all storage allocated and write metadata throughout the space. If that space is not physically available, applications will crash.
There are workarounds for most of these problems in the short term that typically involve configuring an application in a way that disables certain functionality so that it won't conflict with the way thin provisioning operates. Users should obviously assess the potential tradeoffs of configuring applications in this manner against the economic benefits of thin provisioning.
Mid-to-longer-term, as thin provisioning is aggressively adopted, software vendors will embrace thin provisioning because it makes their software easier to manage and cheaper to provision. Larger customers, storage vendors in general and Hitachi in particular should work aggressively with independent software vendors (ISV's) to agree best practice communication between applications and storage in order to accelerate the adoption of thin provisioning. ISV's, storage vendors and customers win with this type of collaboration.
Action item: IT should work aggressively to implement a new way of connecting applications, storage and budget owners. Early adoption of thin provisioning should focus on tier two and tier three applications and on ensuring that the right reporting and business processes are in place to communicate allocated, actual and projected use of storage resources.
A couple more thin provisioning caveats
From The Storage Anarchist, Wednesday, Nov 7, 8:30AM. (updated Nov 10, 8:25AM)
Comments moved to the Thin provisioning: Look before you leap Storage Alert.
Hi I would to know one application that spreads its medatada across the whole allocated storage. In our testing with Oracle, SQL Server, Informix, DB2, Exchange and MySQL as well as various file systems this is not the behavior we've seen.
There are cases where the filesystem will touch the 1st and last block but that is a non-issue given that the last block, in an array with virtualization capabilities and virtual volumes can come from anywhere thus making it a "virtual last block".
NTFS...Correctly stated that NTFS is not particuraly friendly to re-using freed blocks. However, there are vendors out there that have space reclaim capabilities for Windows (i.e Netapp) where they will reclaim blocks freed by the filesystem and still have a TP LUN.
