Finding first, then living off your (storage) body fat
by David Merrill on Jun 17, 2009
IDC recently reported a drop in storage revenue. This could be due to a) economic conditions and restricted capital, b) users are buying the same or more capacity but at lower price points, c) manual and automated reclamation efforts are presented once-stranded capacities, or d) all/none of the above.
I hope that more of option C comes about, because as an industry we are over provisioned and under utilized. Poor utilization has several explanations, and there is not enough room here to go into these reasons, but when average utilization (not allocated) are still hovering in the 30 percentile, there is more that can be done. Economic tough times are encouraging methods and technologies to reclaim existing capacity and to avoid unnecessary capital spending.
Is the idea of using what you already have ‘storage reclamation’ or ‘storage restoration’? A dictionary view of the two terms are different, and perhaps our view of giving back storage to the enterprise can be classified differently as well. The bottom line is this: a TB reclaimed (or restored) is a TB that does not need to be purchased. You can quickly determine the street price of XX TB of capacity, and that would be what you can NOT spend if you are able to recover or restore or reclaim XX TB from what you already have. Using better what you have also improves Return on Asset (ROA).
This is not a new topic on my blog – there is an old blog entry on stop buying storage; and an entry on physical reduction, which is different from reclamation. Then a stand-alone entry on basic disk reclamation; and one from the Storage Architect.
The Economics of Reclamation Process and Technology is very simple:
- Just like server virtualization, storage virtualization can reclaim stranded capacity between frames and present a common pool of storage to various hosts and data service functions
- When tiered storage is available, higher tier capacities can be reclaimed by demoting data or volumes to a lower tier at the appropriate age
- Presenting an integrated archive solution can reclaim disk capacities on any/all tiers and send them to a dedicated, low cost (indexable) tier for long-term cold storage
- Thin volumes can spoof the OS or application by presenting virtual volume capacity while only spending physical pages when real data is needed or written
- Zero page reclamation can be applied when apps or operating systems write out pages of zeros to mark a section of the volume
- Data de-duplication will help with all the data copies that exist
- Then there is the old-stand-by: delete the stuff
These above bullet points (technologies) can be implemented stand-alone, but when bundled present a sum-greater-than-the-parts result in space reclaimed and saved over time. Perhaps these ideas are of interest, but you don’t know where to start. Perhaps you do not know your potential for capacity reclamation in your SAN or NAS environment. Since you cannot improve what you cannot measure, a baseline for the reclamation opportunity is usually the first step.
HDS is announcing this week a new service called Storage Reclamation Services, or SRS. A feature of this service included a limited assessment to an environment up to 5 servers. It is certainly worth a look to see (in a sample size) what the reclamation potential would be through thin provisioning and zero page reclaim. You too can be an economic rock star when you cancel the disk purchase in your budget and reclaim enough capacity to meet your growth needs with what you already have on the floor. That is what Wells Fargo did last year; you can read about it here. Now that Thin Provisioning or Hitachi’s Dynamic Provisioning is available on a modular storage array, there are new entry price points to make this technology closer at hand.
Here are some common trends that I see with customer engagements around the world, as it applied to space reclamation
- Allocation rates to hosts are at a relatively high ratio (60-80% for some), but the underlying usage rate within the allocated volumes is much lower, around 30%
- We have a banking client who is moving active volumes to be thin volumes, and is see a give back rate of usable capacity in the 35-45% range
- Reclamation has everything to do with the OS and the applications that you are running
- Reclamation and zero page reclaim tend to be seen as a one-time event, but periodic analysis of volumes and file systems is suggested
- Incentives and encouragements are needed to get applications or users to move to thinned or virtualized environments
- Lower chargeback is always a good carrot
- Provisioning time can be much faster (even applications can provision themselves) and be a good motivator
- Let the storage consumer see the per-unit-cost-difference to the company with this new technology. Everyone is more socially and economically sensitive to spending these days
- Try before you buy. Make sure the right approach for reclamation is what works best in your environment.