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This is necessary to support "DHT over DHT" configurations, so that the
upper and lower instances of DHT don't step all over each other. Why
would we even consider such a thing? Because it gives us the ability to
do data tiering and rack-aware placement, either by themselves or as
complements to other functionality such as erasure codes or
deduplication which save space but cost performance. By setting up the
top-level DHT to place data into one of several lower-level DHT pools
based on policy instead of pure elastic hashing, we get better
performance for 90% of accesses and better storage efficiency for 90% of
data, all for relatively low effort.
Change-Id: I72e65c29edfc80babf39f7a2a00090f4588c4070
BUG: 924265
Signed-off-by: Jeff Darcy <jdarcy@redhat.com>
Reviewed-on: http://review.gluster.org/4694
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>
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