The Architect’s View Chris M Evans Director, 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….
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 workloadIncreased 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
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