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<div style="color: rgb(0, 0, 0); font-family: arial; font-size:
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-webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;">This
discussion of geo-distributed Swift is of great interest to us as
well. Yet, based on our analysis, the proposed ring of ring seem
to not meet a basic requirement that we see. </div>
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<div style="color: rgb(0, 0, 0); font-family: arial; font-size:
small; font-style: normal; font-variant: normal; font-weight:
normal; letter-spacing: normal; line-height: normal; orphans:
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-webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;">One
of the basic disadvantages (and advantages) of the consistent
hashing at the core of the Swift Ring concept is that it takes
control over the placement of objects. As long as one considers a
fairly unified cluster - and does not care which object is placed
where in that cluster, consistent hashing does a great job.</div>
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<div style="color: rgb(0, 0, 0); font-family: arial; font-size:
small; font-style: normal; font-variant: normal; font-weight:
normal; letter-spacing: normal; line-height: normal; orphans:
auto; text-align: start; text-indent: 0px; text-transform: none;
white-space: normal; widows: auto; word-spacing: 0px;
-webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;">However,
in the case of geo-distributed Swift, many customers do care and
need control over the placement decision - hence making the use of
consistent hashing to decide where an object should be placed will
not do. We actually believe that placement decisions can be made
in the resolution of containers - not individual objects. Hence,
container sync seems like a reasonable starting point.</div>
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small; font-style: normal; font-variant: normal; font-weight:
normal; letter-spacing: normal; line-height: normal; orphans:
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</div>
<div style="color: rgb(0, 0, 0); font-family: arial; font-size:
small; font-style: normal; font-variant: normal; font-weight:
normal; letter-spacing: normal; line-height: normal; orphans:
auto; text-align: start; text-indent: 0px; text-transform: none;
white-space: normal; widows: auto; word-spacing: 0px;
-webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;">We
plan to contribute improvements to container sync, making it a
more attractive, scalable, and easier to use replication mechanism
such that it can serve as a basis of a placement aware system
controlling where replicas reside in a geo-distributed Swift. It
would be great if the the community align on the need to offer
control over placement, between geo distributed sites, but if this
is not the case, we need to find a way to accommodate the
different requirements without complicating the design. </div>
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</div>
<div style="color: rgb(0, 0, 0); font-family: arial; font-size:
small; font-style: normal; font-variant: normal; font-weight:
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-webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;">Regards,</div>
<div style="color: rgb(0, 0, 0); font-family: arial; font-size:
small; font-style: normal; font-variant: normal; font-weight:
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-webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;">David
Hadas <br>
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<pre class="moz-signature" cols="72">--
DH
Regards,
David Hadas
IBM Research Labs, Haifa</pre>
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