Energy-E ciency of Long-term Storage Energy-E ciency of Long-term Storage
Irina Tolokonnikova
Seminar "Energy-E cient Programming" Arbeitsbereich Wissenschaftliches Rechnen Fachbereich Informatik Fakultät für Mathematik, Informatik und Naturwissenschaften Universität Hamburg
2015-01-14
Energy-E ciency of Long-term Storage 2015-03-01
Irina Tolokonnikova
Seminar "Energy-E cient Programming" Arbeitsbereich Wissenschaftliches Rechnen Fachbereich Informatik Fakultät für Mathematik, Informatik und Naturwissenschaften Universität Hamburg
2015-01-14 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage Agenda Archive 1 Archive 2 Data Storage Devices data storage methods Agenda tape Archive HDD MAIDs Agenda 3 State of Research 4 Conclusion
2015-03-01 5 References 1 Archive show the audience what and how much data an archive has to handle with. I want to use the data of the DKRZ given on it's homepage and 2 Data Storage Devices the xkcd-what if? about google data storage methods https://what-if.xkcd.com/63/ tape What is an archive for digital data? How is data stored? and about how HDD much data are we talking about? MAIDs
3 State of Research
4 Conclusion
5 References
Irina Tolokonnikova Energy-E ciency of Long-term Storage 1 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage Archive
Archive storage of digital data for many years requirements: preservation Archive Archive retrieval auditing archival data 6= backup data Archive needs to be cheap to obtain, cheap to operate, easy to expand high costs for energy consumption → room for improvement 2015-03-01
main requirements of an archivebut the main problem of archives are the storage of digital data for many years high costs for energy consumption, and in this talk, we want are going to requirements: see, how we can reduce this costsimprovements are important in this preservation eld, because we want to match the requirements for big data retrieval that means, we want to work with huge amounts of data, compare it and auditing search for association rules e.g. archival data 6= backup data needs to be cheap to obtain, cheap to operate, easy to expand high costs for energy consumption → room for improvement
Irina Tolokonnikova Energy-E ciency of Long-term Storage 2 / 28 DKRZ: > 100 PetaBytes total capacity [1] Google: ∼ 15 ExaBytes (in 2013) = 15000 Petabytes (only estimation)
DKRZ: > 100 PetaBytes total capacity [1] Google: ∼ 15 ExaBytes (in 2013) = 15000 Petabytes (only estimation)
Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage Google Archive Google Archive How much data are we talking about? Google 2015-03-01
how much data is stored in such an archive? rst the data from the DKRZ homepage, to have an anchor for further comparissonsestimashion based on the published energy consumption. Google doesn't publish how much How much data are we talking about? data they store. what if-comic, where peaple can send in absurde but interesting questions, and Randall Munroe will try to answer it. that's more than a lot of data, because in 2013 only 8 ExaBytes of Hard Drives were produced for sale in total worldwide NSA probably stores 1 YotaByte
Irina Tolokonnikova Energy-E ciency of Long-term Storage 3 / 28 Google: ∼ 15 ExaBytes (in 2013) = 15000 Petabytes (only estimation)
Google: ∼ 15 ExaBytes (in 2013) = 15000 Petabytes (only estimation)
Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage Google Archive
How much data are we talking about? Google Archive DKRZ: > 100 PetaBytes total capacity [1] Google 2015-03-01
how much data is stored in such an archive? rst the data from the DKRZ homepage, to have an anchor for further comparissonsestimashion based on the published energy consumption. Google doesn't publish how much How much data are we talking about? data they store. what if-comic, where peaple can send in absurde but interesting DKRZ: > 100 PetaBytes total capacity [1] questions, and Randall Munroe will try to answer it. that's more than a lot of data, because in 2013 only 8 ExaBytes of Hard Drives were produced for sale in total worldwide NSA probably stores 1 YotaByte
Irina Tolokonnikova Energy-E ciency of Long-term Storage 3 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage Google Archive
How much data are we talking about? Google Archive DKRZ: > 100 PetaBytes total capacity [1] Google: ∼ 15 ExaBytes (in 2013) = 15000 Petabytes (only Google estimation) 2015-03-01
how much data is stored in such an archive? rst the data from the DKRZ homepage, to have an anchor for further comparissonsestimashion based on the published energy consumption. Google doesn't publish how much How much data are we talking about? data they store. what if-comic, where peaple can send in absurde but interesting DKRZ: > 100 PetaBytes total capacity [1] questions, and Randall Munroe will try to answer it. that's more than a Google: ∼ 15 ExaBytes (in 2013) = 15000 Petabytes (only lot of data, because in 2013 only 8 ExaBytes of Hard Drives were estimation) produced for sale in total worldwide NSA probably stores 1 YotaByte
Irina Tolokonnikova Energy-E ciency of Long-term Storage 3 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage Google Data Storage Devices Google data storage methods Google 2015-03-01 Figure: 15 ExaBytes of punch cards would be enough to cover New England, to a depth of about 4.5 kilometers but which device should we coose, if we want to store as much data as google does? show some devices, that are not uses for archives and which are Show a real cassette, make clear, why LP or Punch cards are not suitible for long term storage
Figure: 15 ExaBytes of punch cards would be enough to cover New England, to a depth of about 4.5 kilometers
Irina Tolokonnikova Energy-E ciency of Long-term Storage 4 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage not this Data Storage Devices not this data storage methods not this 2015-03-01 Figure: LP [wikipedia.org]
probably not LPs - not easy to search and not as much data, BUT it lasts very long without errors, because it is engraved LPs were send to space, so alien life forms get an impression of the earth, music and human life. It was well chosen, because it had to have a long lifetime
Figure: LP [wikipedia.org]
Irina Tolokonnikova Energy-E ciency of Long-term Storage 5 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage not this Data Storage Devices not this data storage methods not this 2015-03-01
Figure: punch card [wikipedia.org] as we allready learned, punch cards would not be suitible for masses of data
Figure: punch card [wikipedia.org] Irina Tolokonnikova Energy-E ciency of Long-term Storage 6 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage not this Data Storage Devices not this data storage methods not this 2015-03-01 Figure: a United States National Archives Records Service facility in 1959. Each carton could hold 2000 cards [wikipedia.org]
... because than out storage would look like this
Figure: a United States National Archives Records Service facility in 1959. Each carton could hold 2000 cards [wikipedia.org]
Irina Tolokonnikova Energy-E ciency of Long-term Storage 7 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage not this Data Storage Devices not this data storage methods not this 2015-03-01 Figure: 3,5-inch oppy disk
Show, how "normal" cassettes look like and where we know them in every days life. maybe you still know cassetts, but do your younger siblings still know how to use them? explain, that they are still used in another region
Figure: 3,5-inch oppy disk
Irina Tolokonnikova Energy-E ciency of Long-term Storage 8 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage not this? Data Storage Devices not this? data storage methods not this? 2015-03-01 Figure: compact cassette [wikipedia.org]
maybe some of you can remember, that cassetts were used not only for music but also for data in such computers like C64 but the casstetts used for data storage have changed
Figure: compact cassette [wikipedia.org]
Irina Tolokonnikova Energy-E ciency of Long-term Storage 9 / 28 Oracle StorageTek T10000 T2 hold 8,5 TB
Oracle StorageTek T10000 T2 hold 8,5 TB
Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage Tape notetoday cassettes hava a single reel and can store as much data as Hard Discs Data Storage Devices used as a cartridge with a single reel holds several tens to thousands of GB (state wikipedia.org Tape tape 13.01.15) Tape
notetoday cassettes hava a single reel and can store as much data 2015-03-01 as Hard Discs they look like this and are well protected by the case used as a cartridge with a single reel Figure: components of a tape drive [3] holds several tens to thousands of GB (state wikipedia.org 13.01.15)
Irina Tolokonnikova Energy-E ciency of Long-term Storage 10 / 28
Figure: components of a tape drive [3] Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage Tape notetoday cassettes hava a single reel and can store as much data as Hard Discs Data Storage Devices used as a cartridge with a single reel holds several tens to thousands of GB (state wikipedia.org 13.01.15) Tape tape Oracle StorageTek T10000 T2 hold 8,5 TB Tape
notetoday cassettes hava a single reel and can store as much data 2015-03-01 as Hard Discs they look like this and are well protected by the case used as a cartridge with a single reel Figure: components of a tape drive [3] holds several tens to thousands of GB (state wikipedia.org 13.01.15) Oracle StorageTek T10000 T2 hold 8,5 TB
Irina Tolokonnikova Energy-E ciency of Long-term Storage 10 / 28
Figure: components of a tape drive [3] Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage DKRZ 7 automated Oracle/StorageTek SL8500 tape libraries 8 robots per library Data Storage Devices over 67000 slots for magnetic tape cassettes DKRZ tape DKRZ 2015-03-01 7 automated Oracle/StorageTek SL8500 tape libraries Figure: Inside the Tape library of DKRZ [1] 8 robots per library over 67000 slots for magnetic tape cassettes main summery about tape
Figure: Inside the Tape library of DKRZ [1]
Irina Tolokonnikova Energy-E ciency of Long-term Storage 11 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage lifetime and costs lifetime: 30 years costs: less than 1 cent per GB Data Storage Devices 238X less energy over 12 years than HDD lifetime and costs tape lifetime and costs
lifetime: 30 years 2015-03-01 costs: less than 1 cent per GB Figure: upgrades save money and space [3] 238X less energy over 12 years than HDD main point, why tape is used for long term storageWhen not in use, tape doesn't produce any energy and doesn't need any ether it is important to upgrade the device, even if it hase a long lifetime, because you can save much space, as shoven in this graphic
Irina TolokonnikovaFigure: upgrades saveEnergy-E ciency money and of Long-term space [3] Storage 12 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage pros and cons Data Storage Devices Pros Cons cheap needs special pros and cons tape expensive equipment long lifetime sequential access pattern pros and cons no power needed when not accessed 2015-03-01
Tape has to be rewinded when searched and needs much more time to get to information, even if you know, where it is stored. Pros Cons Even more time is needed, if you want to search for data or compare it. cheap needs special expensive equipment long lifetime sequential access pattern no power needed when not accessed
Irina Tolokonnikova Energy-E ciency of Long-term Storage 13 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage Hard Drives easy and fast to access data storage searching, consistency checking and inter-media reliability Data Storage Devices operations costs: 0.07 $per GB and falling Hard Drives HDD lifetime: 10 years, but easy to break mechanics Hard Drives
easy and fast to access data storage 2015-03-01
Figure: Laptop Hard disk drive, 500 GB Western Digital Scorpio searching, consistency checking and inter-media reliability [wikipedia.org] operations Same for Hard drives, but in this case a real object is not needed, costs: 0.07 $per GB and falling because every one of you probably has one ore more at homethe costs get lifetime: 10 years, but easy to break mechanics higher, when we need to change the Discs more often and when we need redundancy to save data, in case one discs breakesnormal HDD, like in most of your laptops probably
Figure:Irina TolokonnikovaLaptop Hard disk drive, 500Energy-E ciency GB Western of Long-term DigitalStorage Scorpio 14 / 28 [wikipedia.org] Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage pros and cons Data Storage Devices Pros Cons easy access, simply system needs much power, pros and cons HDD even when turned o matches requirements of big data easy to break higher bandwidth (200X) needs extra space pros and cons for redundancy 2015-03-01
summery about HDD, main points relevant for long term storage when storing on HDD the main point to remember is, that extra space Pros Cons for redundancy is need, and that's why more space is needed for the easy access, simply system needs much power, devices, than we would estimate from raw data amount. even when turned o matches requirements of big data easy to break higher bandwidth (200X) needs extra space for redundancy
Irina Tolokonnikova Energy-E ciency of Long-term Storage 15 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage Colarelli, Grunwald et al.(2002)
Data Storage Devices massive array of idle disks = MAIDs aim: storage densities matching those of tape, with reduced Colarelli, Grunwald et al.(2002) energy consumption MAIDs but operating same data volume in disks costs 10X more than in tape idea: use a cache manager to keep only part of disks in an Colarelli, Grunwald et al.(2002) array powered up varying spin-down delays 2015-03-01
a newer approach on handling HDD energy e ciently. an important massive array of idle disks = MAIDs article, cited in following research articles dealing with the question, how we can store on HDD more e ciantly, aim: storage densities matching those of tape, with reduced maybe someday as eddiciant as on tapewhen using only the disks already energy consumption spinning, we can save energy. but operating same data volume in disks costs 10X more than previos observation: mostly searched information is thoes just saved or in tape added. So by keeping this information in cache we probably can manage idea: use a cache manager to keep only part of disks in an most of the requests ...to save extra energy array powered up varying spin-down delays
Irina Tolokonnikova Energy-E ciency of Long-term Storage 16 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage Results Data Storage Devices
good trade o in performance and energy e ciency Results MAIDs read performance still eected by the spin-down delay but 82% of read requests were satis ed by the cache Results least energy consumed with 4 sec spin-down delay 2015-03-01
what are the main points about MAIDsusing MAIDs the HDD might still not be as e ciant as tape, but it's a good approach to work on
good trade o in performance and energy e ciency read performance still eected by the spin-down delay but 82% of read requests were satis ed by the cache least energy consumed with 4 sec spin-down delay
Irina Tolokonnikova Energy-E ciency of Long-term Storage 17 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage SSD Data Storage Devices
costs: 0.66 $per GB , yet too expensive SSD MAIDs lifetime depends on usage, ∼10 years yet unclear, how unused data behaves on SSD SSD coming soon? 2015-03-01
looking forward: will we use SSD in some years? other possible storage devices are coming, but that it is not yet clear, if good for storage and how fast information gets lost on SSD costs: 0.66 $per GB , yet too expensive lifetime depends on usage, ∼10 years yet unclear, how unused data behaves on SSD coming soon?
Irina Tolokonnikova Energy-E ciency of Long-term Storage 18 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage Pergamum tomes by Storer et al. (2008) interfaces and protocols change slowly using inter- and intra-device redundancy State of Research work energy e cient, by not spinning up idle disks → intelligent, self managing storage device Pergamum tomes by Storer et al. (2008) Pergamum Pergamum tomes by Storer et al. (2008)
interfaces and protocols change slowly 2015-03-01 Figure: Pergamum tome, redrawn using inter- and intra-device redundancy newer research and what will maybe be the future of long term storage work energy e cient, by not spinning up idle disks talk about, how HDDs can be made more e cient but still t Big Data → intelligent, self managing storage device Named after the library of Alexandria main ideas of this paper are based on thoes about MAIDsUse the fact, that interfaces and protocols take much more time to change. Just thin of http ... not only for restoring data, which was saved on broken devices, but also for reading
Figure: Pergamum tome, redrawn
Irina Tolokonnikova Energy-E ciency of Long-term Storage 19 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage Results of Pergamum
size of the hard drive State of Research nonvolatile RAM handles many types of requests(e.g. hashes) without spinning up the disk using signatures for redundancy checking in entire inter-disk Results of Pergamum Pergamum group using trees of hash values to reduce signature data once added to the network, the tome automatically joins a Results of Pergamum redundancy group or builds new one → makes storage management easier using intra-device redundancy, recovering from small errors without other devices 2015-03-01 aim to be price-competitive with tape size of the hard drive nonvolatile RAM handles many types of requests(e.g. hashes) main points about the Pergamum tome, that can help improve it in futuresmall and cheapenergy e ciant itselfgood algorithm helps reducing without spinning up the disk the energyonly a minimum trained administrator needed to change the using signatures for redundancy checking in entire inter-disk broken devices once a month. group the new devices will organise themselves in existing groups or start new using trees of hash values to reduce signature data onesthis goal is not reached (yet?) once added to the network, the tome automatically joins a redundancy group or builds new one → makes storage management easier using intra-device redundancy, recovering from small errors without other devices aim to be price-competitive with tape
Irina Tolokonnikova Energy-E ciency of Long-term Storage 20 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage Problems and improvments
State of Research still not included in data archives(?) redundancy overhead, but much energy saved Problems and improvments Pergamum "disposable" tomes encoding time 10X longer than on laptop processor BUT 10X less power consumed future work: Problems and improvments better algorithms parallel processes (distributed searching) 2015-03-01
I don't know much about this point, and I couldn't nd anything about still not included in data archives(?) thisare desposable devices realy more energy e ciant and saving money? redundancy overhead, but much energy saved Do we realy want so throw that much HHDs away?future tasks named in paper "disposable" tomes encoding time 10X longer than on laptop processor BUT 10X less power consumed future work: better algorithms parallel processes (distributed searching)
Irina Tolokonnikova Energy-E ciency of Long-term Storage 21 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage A Spin-Up Saved is Energy Earned, Greenan et al.(2008) idea: use redundancies on active devices instead of waking up inactive ones State of Research → Power aware coding three conditions needed: A Spin-Up Saved is Energy Earned, Greenan et al.(2008) power aware coding A Spin-Up Saved is Energy Earned, Greenan et
idea: use redundancies on active devices instead of waking up 2015-03-01 al.(2008) Figure: Three conditions for a power-aware system inactive ones based on "A spin-up saved is Energy earned" paper by Greenan et al. → Power aware coding three conditions needed: (2008). It's slightly newer and i also presents some algorithms. But I nd it a little confusing and I think, it would be too much, if I explained it in detail, so here is only a summary of the main ideas, with pictures I made to illustrate them
Figure: Three conditions for a power-aware system
Irina Tolokonnikova Energy-E ciency of Long-term Storage 22 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage Power Aware Techniques
rules known from Pergamum tome State of Research Power Schedule each code instance should have own write policy write parallel across disk groups Power Aware Techniques power aware coding Power-Aware Read Algorithm minimize the number of disk activations rst nd out, if lost data is recoverable like solving a matrix where inactive devices are treated as Power Aware Techniques erased Disk Activation Algorithm perform search to nd best activation
2015-03-01 how and when is a spin-down performed?
rules known from Pergamum tome Power aware Techniques as named in paperalready used in Pergamum Power Schedule and learned from Storer et al., since this paper is also citing the each code instance should have own write policy Pergamum-paper write parallel across disk groups Power-Aware Read Algorithm minimize the number of disk activations rst nd out, if lost data is recoverable like solving a matrix where inactive devices are treated as erased Disk Activation Algorithm perform search to nd best activation how and when is a spin-down performed?
Irina Tolokonnikova Energy-E ciency of Long-term Storage 23 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage observation while testing mind the trade-o trilemma! State of Research observation while testing power aware coding
observation while testing Figure: the trade-o when trying power aware coding open questions: which enviroments will bene t from power aware coding?
2015-03-01 how to nd optimal policies? mind the trade-o trilemma! robust metrics have to be developed for evaluation the power-reliability-performance trade-o it's not called trilemma in the paper, that's my interpretation of it and the main point I want the audience to keep in mind: You allways habe trade-os, be aware where you want to have them.important point for future research
Figure: the trade-o when trying power aware coding
open questions: which enviroments will bene t from power aware coding? how to nd optimal policies? robust metrics have to be developed for evaluation the power-reliability-performance trade-o
Irina Tolokonnikova Energy-E ciency of Long-term Storage 24 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage Conclusion Conclusion Conclusion Conclusion 2015-03-01 Figure: Disk compared to Tape [3]
Figure: Disk compared to Tape [3]
Irina Tolokonnikova Energy-E ciency of Long-term Storage 25 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage Conclusion Conclusion Pergamum tomes by Storer et al. Pergamum tomes added to networks redundancy overhead used to recover errors energy saved by not spinning up other disks Conclusion self managing system with "disposable" nodes Power Aware Programming try to use less disks as e cient as you can mind the trade-o trilemma between fault tolerance, space Conclusion e ciency and power e ciency "Initial results show that power-aware coding may be well suited for the write-once, read-maybe workload of long-term archival storage systems." 2015-03-01
Pergamum tomes by Storer et al. In the summery I want to present the pros and cons of tape and HDD Pergamum tomes added to networks and on which data or in which ldes which seems to be the better choise. redundancy overhead used to recover errors Also I want to remind, that the life time of the device chosen should not energy saved by not spinning up other disks be forgotten self managing system with "disposable" nodes this would be the basic slid for discussion this quote shows, that you always have to keep in mind, how and how often you want to reuse the Power Aware Programming stored information try to use less disks as e cient as you can if you want to rearch for data or compare random les or look for mind the trade-o trilemma between fault tolerance, space e ciency and power e ciency association rules e.g., you will have to calculate with higher energy "Initial results show that power-aware coding may be well consumption suited for the write-once, read-maybe workload of long-term archival storage systems."
Irina Tolokonnikova Energy-E ciency of Long-term Storage 26 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage How would you store... Conclusion How would you store...... (your own) private medical data? ...research data of a medical study? How would you store...... data of all patients of a hospital? 2015-03-01
Instead of a slide whit "Any questions? Thanks for listening" I want to end with a question, the audience should answer for themselves, which device they would choose. ...(your own) private medical data? ...research data of a medical study? ...data of all patients of a hospital?
Irina Tolokonnikova Energy-E ciency of Long-term Storage 27 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage How would you store... Conclusion
...(your own) private medical data? ...research data of a medical study? How would you store...... data of all patients of a hospital? 2015-03-01
Instead of a slide whit "Any questions? Thanks for listening" I want to end with a question, the audience should answer for themselves, which device they would choose.
Irina Tolokonnikova Energy-E ciency of Long-term Storage 28 / 28 Archive Data Storage Devices State of Research Conclusion References Energy-E ciency of Long-term Storage References [1] https://www.dkrz.de/Klimarechner-en/datenarchiv (13.01.2015) [2] https://what-if.xkcd.com/63/ (13.01.2015) References [3] Dr. Mark L Watson: Advanced Tape Technologies for Future Archive Storage Systems. MSST - Media II (Tape Media and Libraries), 2013 References [4] Colarelli, Dennis, Dirk Grunwald, and Michael Neufeld. The case for massive arrays of idle disks (maid). The 2002 Conference on File and Storage Technologies. 2002. [5] Storer, Mark W., et al. Pergamum: Replacing tape with energy References e cient, reliable, disk-based archival storage. Proceedings of the 6th USENIX Conference on File and Storage Technologies. USENIX Association, 2008.
2015-03-01 [6] Greenan, Kevin M., et al. A Spin-Up Saved Is Energy Earned: [1] https://www.dkrz.de/Klimarechner-en/datenarchiv (13.01.2015) Achieving Power-E cient, Erasure-Coded Storage. HotDep. 2008. [2] https://what-if.xkcd.com/63/ (13.01.2015) [3] Dr. Mark L Watson: Advanced Tape Technologies for Future Archive Storage Systems. MSST - Media II (Tape Media and Libraries), 2013 [4] Colarelli, Dennis, Dirk Grunwald, and Michael Neufeld. The case for massive arrays of idle disks (maid). The 2002 Conference on File and Storage Technologies. 2002. [5] Storer, Mark W., et al. Pergamum: Replacing tape with energy e cient, reliable, disk-based archival storage. Proceedings of the 6th USENIX Conference on File and Storage Technologies. USENIX Association, 2008. [6] Greenan, Kevin M., et al. A Spin-Up Saved Is Energy Earned: Achieving Power-E cient, Erasure-Coded Storage. HotDep. 2008.
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