Energy Efficient Storage Technologies for Data Centers Alan G. Yoder, Ph.D. NetApp
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Transcript of Energy Efficient Storage Technologies for Data Centers Alan G. Yoder, Ph.D. NetApp
Energy Efficient Storage Technologies for Data Centers
Alan G. Yoder, Ph.D.NetApp
Chair, SNIA Technical Council
Energy Efficient Storage Technologies for Data Centers© 2010 Alan G. Yoder. All Rights Reserved.
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Abstract
Energy Efficient Storage Technologies for Data CentersAn impressive amount of work has been done to date on improving the electrical efficiency of various data center components. The data storage industry has begun to see the fruits of this effort, with increased power supply and fan efficiencies. However, storage presents other significant opportunities for energy conservation, through various types of capacity optimization, that are not captured in electrical efficiency discussions. As data storage uses on the order of 25% of IT power in an average data center, these other opportunities bear examination. This article presents a survey of emerging storage technologies which positively impact energy usage and presents current thinking in the storage industry regarding their relative effectiveness. It also attempts to set a baseline for configurations against which improvements in capacity and energy use can be made.
Energy Efficient Storage Technologies for Data Centers© 2010 Alan G. Yoder. All Rights Reserved.
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Outline
Purpose of paperWhat is “storage”?What is “storage efficiency”?Baseline data center storage configurationStorage optimizing technologiesBallpark savings guesstimatesSNIA activitiesConclusion
Energy Efficient Storage Technologies for Data Centers© 2010 Alan G. Yoder. All Rights Reserved.
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Purpose of paper
Introduce storage as a separate and special problem in energy efficiency
Data at rest requirements
Set baseline for comparison of purported improvementsEstablish a taxonomy for ways of saving energySurvey of what industry has been doing in the area of energy efficiency
Energy Efficient Storage Technologies for Data Centers© 2010 Alan G. Yoder. All Rights Reserved.
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What is “storage”?
At homeApple Time Machine + 2 USB drives (one offsite)
In the labLinux/BSD box and a few SATA drives
In the data centerHi performance (both latency and bandwidth)Petabyte scaleRAS (reliability, availability, serviceability)
5 9’s availability or better (< 5 min unplanned downtime / yr)RPO of minutes or less (sometimes zero)RTO of minutesnon-disruptive firmware and hardware upgrades
Something always broken, yet life goes on
Energy Efficient Storage Technologies for Data Centers© 2010 Alan G. Yoder. All Rights Reserved.
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What is “storage efficiency”?
Electrical efficiencyHow much heat is generated during the conversion of electrical energy into useful work?Good for CPUs, maybe for data in flight
Storage efficiencyHow much data can be crammed into a box using a given amount of electricity and raw capacity(Definitions are still a work in progress)
All based around sizeof(data) and sizeof(raw capacity)
Energy Efficient Storage Technologies for Data Centers© 2010 Alan G. Yoder. All Rights Reserved.
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Baseline configuration
No single point of failure (no SPOF)*everything* is redundantRAID 1dual pathingpower supplies operate at 50% load (or less)
No system-wide reboots*everything* is hot-swappable
High performance (SAN emulates Direct Attach)
Fibre Channel drives
Energy Efficient Storage Technologies for Data Centers© 2010 Alan G. Yoder. All Rights Reserved.
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Summary of baseline configuration
No SPOFRAID 1FC drives
This configuration has ruled Tier 1 storage in the data center for 15 yearsEmphasis on performance and data safety
Energy Efficient Storage Technologies for Data Centers© 2010 Alan G. Yoder. All Rights Reserved.
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Storage optimizing technologies
Electrical efficiencyDisk spindownPower supply and fan efficiency, andSSDs
Capacity optimizationDelta snapshotsThin provisioningAdvanced RAIDData deduplicationCompression
Hybrid systemsSlow SATA drives + flash
Energy Efficient Storage Technologies for Data Centers© 2010 Alan G. Yoder. All Rights Reserved.
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A nod to facilities optimization
Usually the most energy savings are gotten here
PUE = ratio of input power to IT power
Traditional PUE: 2.25 and upModern PUE: 1.2
Air economizers, variable speed fans, flywheel UPSs, etc.Savings of over 50% often possible
Impossible to obtain with IT equipment optimizations assuming old-style power delivery inefficiencies (PUE > 2.0)
Energy Efficient Storage Technologies for Data Centers© 2010 Alan G. Yoder. All Rights Reserved.
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Storage Efficiency: 4 techniques
Make the equipment more energy efficientUse less redundancyCommit less spaceSqueeze more data into available space
Energy Efficient Storage Technologies for Data Centers© 2010 Alan G. Yoder. All Rights Reserved.
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Making equipment more energy efficient
Power supply efficiency80plus, Climate Savers, US EPAEfficiencies driven from ~65% to ~90% and up
Variable speed fansPower theoretically quadratic in rotational speedGreat opportunityNot enough operational data to date
Disk spindownLooks great on paper; problematic in practice
RAID groups, background housekeepingOnly suitable for secondary storage due to latency hit
So far not viable in marketplace
Energy Efficient Storage Technologies for Data Centers© 2010 Alan G. Yoder. All Rights Reserved.
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Better energy efficiency (cont.)
SSDsSeemingly ideal
Zero data at rest energy (caveat: housekeeping requirements an open question)Data in flight energy scales with IOPs
Price barriers to widespread adoption
High-capacity drives with flashPerformance about as good as FC
No free lunch caveat: except when at write saturation
1/6 the energy density of FC at restQuestion: will the flash migrate to the host?
Energy Efficient Storage Technologies for Data Centers© 2010 Alan G. Yoder. All Rights Reserved.
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Using less redundancy
RAID 150% space efficiency
Storage bricks (Google et al)typically 33% or less
similar to RAID 1 + online backupmuch worse if CPUs aren’t occupied with useful work
RAID 5Recommended raid group size of 5 to 880% to 88% efficiency
RAID 6Recommended raid group size of 10 to 1680% to 88% efficiencyMoving to this because of convergence of BER and disk size on modern systems ~4% chance annually of 2nd disk failure during RAID reconstruct on a 100-disk array
Energy Efficient Storage Technologies for Data Centers© 2010 Alan G. Yoder. All Rights Reserved.
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Using less redundancy (cont.)
• Delta snapshots– shared-data PIT copies– technology is similar to vfork– read-only and read-write variants– many data protection and what-if scenarios
satisfied with deltas instead of full copies
Energy Efficient Storage Technologies for Data Centers© 2010 Alan G. Yoder. All Rights Reserved.
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Committing less space
• Thin provisioning– Works similarly to user quotas in filesystems– Impressive gains, because
• Volumes are overprovisioned (more space for files than used)
• Systems are overprovisioned (more space for volumes than used)
Energy Efficient Storage Technologies for Data Centers© 2010 Alan G. Yoder. All Rights Reserved.
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Squeezing more data into available space
• Compression– Harder on block storage (quantization)
• Deduplication– Savings are most impressive on secondary
storage– Global dedup an unsolved problem
• Communication, index overhead• You *better* not lose that base copy!
Energy Efficient Storage Technologies for Data Centers© 2010 Alan G. Yoder. All Rights Reserved.
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Average savings (from baseline or historical figures)
Technology SavingsFacilities optimization 50% Power supply improvements 20%Variable speed fans unknownLarge capacity drives 80%Advanced RAID 40%Delta snapshots 90% +Thin provisioning 50%In-place data deduplication 27% (Netapp: 1 exaByte)
Compression 20% +
Energy Efficient Storage Technologies for Data Centers© 2010 Alan G. Yoder. All Rights Reserved.
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Storage procural politics
• IT guys don’t pay utility bill (OPEX)– So they don’t care how power efficient the
storage is until they hit a density wall
• Capacity optimizing technologies affect CAPEX as well as OPEX
– Capacity optimizing technologies allow them to buy less gear to store the same data
– IT guys do care about this
Energy Efficient Storage Technologies for Data Centers© 2010 Alan G. Yoder. All Rights Reserved.
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SNIA activities
• GSI – Green Storage Initiative– Collect and harmonize industry feedback for US EPA– Evangelize technical work– Develop labeling program
• Green TWG – Technical Working Group– IP-protected group– Idle and active power metrics
• Capacity Optimization subgroup (of TWG)– Characterization of capacity optimization technologies
• Tutorials, whitepapers, etc.– At SNW trade shows, in FarSighted magazine
Energy Efficient Storage Technologies for Data Centers© 2010 Alan G. Yoder. All Rights Reserved.
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Baseline configuration revisited
• For research into data center class storage– Disk subsystems
• No SPOF in shelves• Multipathing• RAID 6 (or 5 if 6 is unavailable)• 100 or more disks
– Controllers• No SPOF• Multipathing• Multiprotocol (NFS + CIFS)• Thin provisioning, delta snapshots, compression,
dedup all operational
Energy Efficient Storage Technologies for Data Centers© 2010 Alan G. Yoder. All Rights Reserved.
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Questions