Upload
pratik-mahajan
View
217
Download
0
Embed Size (px)
Citation preview
8/17/2019 Consistency As A Service: Trading Consistency for Availability
1/5
Consistency As A Service: Trading Consistency for Availability
Pratik S. Mahajan
Department of CSE, Government College of Engineering, Aurangabad, India
Email: csepratikmahajangmail!com
Shubhangi Sapkal
Department of "CA, Government College of Engineering, Aurangabad, India
Dr. . . Desh!ukh
Department of CSE and I#, Dr! $A"%, Aurangabad, India
Abstract & As more and more charities and libraries move to
cloud services, this technolog' is no longer novel( it)s becoming the dominant paradigm in I#! A cloud storage facilit'is a need of an hour as it facilitates elasticit'&so resourceallocation can get bigger or smaller depending on a users*demand, Elasticit' enables scalabilit'&so that the cloud canscale up +hen demand is high and do+n for less demand e!g!
allo+s for scale +hen an application in the cloud adds users,etc!-, .esource /ooling, 0n Demand, Self1Service /rovisioningi!e client can re2uest desire service from cloud vendor and3456 service i!e high availabilit' at cheapest price !$ut the ke'hindrance come +hen +e need high availabilit'(as it needed tocreate plent' of copies of single file and at different
geograph' !#o attain high consistenc' more mone' is needed!In this paper, +e have presented uni2ue, innovative, efficientand effective consistenc' as a service CaaS- model, +hichconsists of a various large capacit' data clouds and small auditclouds !Data clouds are used to store clients actual data offered b' Cloud vendors like Google, Ama7on, "icrosoft, etc !and
Audit cloud are used to check consistenc' of cloud ismaintained accuratel' or not! At the last +e have appliedtraditional approach to audit purpose i!e 8euristic AuditingStrateg' +hich uses 3 algorithm vi7 9ocal and Global AuditingStrateg'! 9oosel' s'nchroni7ed clock is needed to audit purpose! 8euristic Auditing Strateg' is used to find violations
in consistenc' terms i!e! document is modified or safe!
e'+ords & Audit Cloud, Consistenc' as a service CaaS-,
Data Cloud, Global Auditing, 9ocal Auditing!
I! I;#.0D%C#I0;
Cloud Computing is still a bu77+ord or uncleared to man' people!#he definition mostl' used toda' is the one e? meanseither +e can provide availabilit' or consistenc' #here are man' differences in Cloud Computing andtraditional transactional databases related to consistenc'
re2uirement! As in cloud, there is data duplication is taken place i!e! data is geographicall' distributed to get higher
Page "
https://en.wikipedia.org/wiki/Disk_imagehttps://en.wikipedia.org/wiki/Disk_imagehttps://en.wikipedia.org/wiki/Block_storagehttps://en.wikipedia.org/wiki/Object_storagehttps://en.wikipedia.org/wiki/VLANhttps://en.wikipedia.org/wiki/VLANhttps://en.wikipedia.org/wiki/Disk_imagehttps://en.wikipedia.org/wiki/Disk_imagehttps://en.wikipedia.org/wiki/Block_storagehttps://en.wikipedia.org/wiki/Object_storagehttps://en.wikipedia.org/wiki/VLANhttps://en.wikipedia.org/wiki/VLAN
8/17/2019 Consistency As A Service: Trading Consistency for Availability
2/5
degree of performance! $ut duplicated file needs strongconsistenc' to keep the consistenc' bet+een a file and itsreplicas and simultaneousl' the overhead of consistenc'
maintenance is determined b' the number of replicas!Connecting these t+o components +ill increase the s'stem performance! Consistenc' is ensured b' s'nchroni7ation
bet+een the copies! Consider the scenario in Fig!@, +here .aj and Simran+orking on single project together using cloud facilit' +here
data is replicated to distributed data servers CS@, CS3, CS,CS4,and CS! After uploading a ne+ version of there2uirement anal'sis to a CS 4,Simran calls .aj to do+nload
the latest version for integrated design! 8ere, after Simran calls.aj, the causal relationship ? is established bet+een
Simran*s
update and .aj*s read! #herefore, the cloud should providecausal consistenc', +hich ensures that Simran*s update iscommitted to all of the replicas before .aj*s read! If the cloud provides onl' eventual consistenc', then .aj is allo+ed toaccess an old version of the re2uirement anal'sis from CS!If
the old version is used,it ma' not satisf' the customer*sactual re2uirement!
As per the Cloud Computing feature data should availableal+a's to the client +hich are replicated at multiplegeographical locations! #he main problem +ith consistenc'feature of cloud( it costs ver' high to attain strong consistenc'means updated cop' present al+a's to the client! So most of
the cloud vendors provide +eak consistenc' like eventualconsistenc', +here client sees slightl' old data! Eventualconsistenc' provides ver' high reliabilit' and high performance +hich is the re2uirement of domain name s'stem!%pdates to a name +ill not be visible immediatel', but allclients are ensured to see them eventuall'!
8o+ever, eventual
consistenc' is not a catholicon for all applications! Especiall'for the interactive applications, stronger consistenc' assuranceis of increasing importance! $ut different applications re2uireddifferent consistencies like mail services need monotonic readconsistenc' and read 'our +rite consistenc' +hile socialnet+ork need causal consistenc'!
!
Fig.1: An application that requires causal consistency.
.
II! .E9A#ED H0.
A cloud is essentiall' a large1scale distributed s'stem
+here each piece of data is replicated on multiplegeographicall'1 distributed servers to achieve highavailabilit' and high performance! #hus, +e first revie+the consistenc' models in distributed s'stems! As a
standard te
8/17/2019 Consistency As A Service: Trading Consistency for Availability
3/5
Concurrent +rites ma' be seen in a different order on differentmachines!
Client centric consistenc' models Concerns consistenc'e
8/17/2019 Consistency As A Service: Trading Consistency for Availability
4/5
All other users +ill send their %0#s to the auditor for
obtaining a global trace of operations! After e
8/17/2019 Consistency As A Service: Trading Consistency for Availability
5/5
Fig. & Auditing 'eport
B! C0;C9%SI0;
Consistenc' as a service CaaS- model and a t+o1level auditingstructure to help users validate +hether the cloud service provider CS/- is providing the promised consistenc' and to2uantif' the severit' of the violations is an' !Hith the CaaSmodel, the users can assess the 2ualit' of cloud services andselect a right cloud service provider among various candidates ,
for e in /roc! 3OO6 AC" S0S/!?6Rin 9iu, Guojun Hang ,>Consistenc' As A Service:Auditing Cloud>, IEEE #ransactions 0n ;et+ork And
Service "anagement, Bol! @@, ;o! @, "arch 3O@4!
Page &