- Virtualization is driving increased storage needs due to server consolidation and high I/O density workloads like VDI. This requires consistent high performance from storage. - Flash/SSD storage provides very high IOPS and low latency needed for virtualized environments but comes at a higher cost per GB than HDDs. It is better to evaluate storage on a cost per IOPS basis. - There are different approaches for using flash including all-flash arrays, hybrid arrays with flash acceleration tiers, and server-side flash drives. Control of data placement and management is also shifting from storage arrays to hypervisors.

1. The Architect’s View
Chris M Evans
Director, Langton Blue Ltd
blog.thestoragearchitect.com
@chrismevans

2. Introduction
• I am an independent consultant 
• I have no marketing budget – no giveaways 
• I don’t know everything (although my wife
says I think I do) 
• Let’s make this interactive 
I realise I am between you and lunch….

3. The Need for Virtualisation….

4. Our Topic for Today…
• Last time I presented you the past….

5. Our Topic for Today…
• Today I give you – The Future!

6. How is Virtualisation Driving Storage Use?
• High I/O density
– Consolidation of servers and IOPS into single LUNs
– VDI desktop consolidation
– Array based copy (VAAI)
• High Concentration of Risk
– Multiple dependent systems in one server/cluster
• Consistent Performance
– No I/O spikes – bad for any workload, catastrophic for gaming &
financial workloads
• I/O Blender
– Virtualisation creates highly random workload
Increased levels of virtualisation require significant improvements in
I/O density

7. Requirements
• Consistent high performance
– Low latency – 1ms or less
– High IOPS > 500K
– Reliability – no failures
• Management
– APIs & RESTful interfaces
– Private Cloud integration
• Advanced Features in Arrays
– VAAI, VASA support

8. Enter Flash!
• Solid State Storage
• Very high IOPS – both read and write
• Low latency
• Low Power
• “enterprise” SLC and consumer “MLC” grade
• SAS/SATA form factor compatible
• Great at managing random workload….
But…..
• Relatively high cost (SLC especially so)
• Finite lifetime – they will wear out and fail

9. How Can Flash Be Used?
• In-Server
– PCIe SSD – Fusion-IO, VFCache, etc
– SAS SSD devices
– Very high low latency, local performance
– Data is isolated in the server, not shared between
members of a cluster
– No redundancy in the case of failure
Great solution if you can tolerate some failure & data loss
(web cache)
In-Server SSD usage will rely on application integration

10. How Can Flash Be Used?
• Enhance existing storage
– SSD in existing traditional arrays
– Quick solution
– Either partially or entirely fill an array
– May not get best performance from SSD
– Requires automated tiering to get best results
• Dynamic Tiering, e.g. EMC’s FAST

11. How Can Flash Be Used?
• Dedicated SSD arrays
– New vendors and products coming to market
– All flash solid state devices
– Hardware tuned to work with solid state media
• I/O Spike avoidance
• Wear levelling
• RAID & controller redundancy
– Consistent performance with scale
• IOPS & Latency
– Next wave of products will bring scale to match
performance

12. It’s About $/IOPS not $/GB
• Cost models need to evolve
– $/GB doesn’t work for SSD today, HDD still
cheaper
– Vendors using tricks (like post-dedupe and
compression capacity) to fix $/GB numbers
• Better comparison is $/IOPS
– Have to quantify cost benefit of faster I/O
– Can be justified in certain workloads

13. Vendors With Products Today

14. The Drawbacks
• Is this a hammer to crack a nut?
– All SSD means all data is expensive
– What about low priority I/O?
– What about inactive data?
– What about secondary data copies?
– What about replication?
Is there another way?

15. The Mavericks
• Some vendors are taking alternative
approaches
– Virsto – random to sequential workload
– Atlantis Computing – I/O reduction
– Tintri – VMware aware storage
– Nutanix – Hybrid storage & hypervisor

16. Migration of Control
• With SAN, storage arrays owned the data
– Decided on placement
– Managed clones and replication
– Managed redundancy/failover
• With Virtualisation, control shifts to the
hypervisor
– Storage capabilities advertised with VASA
– Data replication with VAAI
– Data placement with Storage DRS
– Bandwidth/throughput management with Storage I/O
Control

17. Where Should Control Lie?
• Both array and hypervisor now allow for
– Thin Provisioning
– Tiered Storage
– Initial and Dynamic Data placement
– Replication
Where should control lie? Open Question – I don’t
have an answer, but I have an opinion!

18. What about DAS & NAS?
• Nothing wrong with NAS or DAS but…
– There are no all-flash NAS arrays (yet)
– DAS is just SSD in the server with the same issues
of reliability of a single device
• NAS & DAS have a place, but not with high-
performance/high-density deployments
Ultimately the protocol is less relevant than
the service capabilities of the storage

19. The Future
• SSD is here to stay
• So are Hard Drives – cheap and easy
• All-SSD arrays have to evolve
– 90% Flash as primary storage
– 10% HDD as archive of inactive working set
• It’s not fully clear whether storage arrays will require
advanced functionality in all-virtualised environments
• Application vendors will be heavily involved
• Big issues still to solve
– Long distance replication
– Proper DR

20. Questions/Thoughts/Opinions?
• Follow up questions;
– chris@brookend.com
– http://blog.thestoragearchitect.com
– @chrismevans