The Architect’s View

Chris M EvansDirector, Langton Blue Ltd

blog.thestoragearchitect.com@chrismevans

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….

The Need for Virtualisation….

Our Topic for Today…

• Last time I presented you the past….

Our Topic for Today…

• Today I give you – The Future!

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

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

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

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

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

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

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

Vendors With Products Today

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?

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

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

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!

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

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

Questions/Thoughts/Opinions?

• Follow up questions;– chris@brookend.com– http://blog.thestoragearchitect.com– @chrismevans