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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>
<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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<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>
<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;
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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:
normal; letter-spacing: normal; line-height: normal; orphans:
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white-space: normal; widows: auto; word-spacing: 0px;
-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:
normal; letter-spacing: normal; line-height: normal; orphans:
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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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