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From Ketan Dixit <ketan.di...@gmail.com>
Subject Re: Namespace partitioning using Locality Sensitive Hashing
Date Tue, 02 Mar 2010 02:59:44 GMT
Folks,

I am still wondering why would an LSH (Locality Sensitive Hashing)
based partitioning scheme provide better scalability than a normal
cryptographic hash scheme. Is there a chance that LSH will offer
better performance than a normal one?

Best,
Ketan

On Mon, Mar 1, 2010 at 9:15 PM, Eli Collins <eli@cloudera.com> wrote:
> On Mon, Mar 1, 2010 at 5:42 PM, Ketan Dixit <ketan.dixit@gmail.com> wrote:
>> Hello,
>> Thank you Konstantin and  Allen for your reply. The information
>> provided really helped to improve my understanding.
>> However I still have few questions.
>> How Symlinks/ soft links are used to solve the probem of partitioning.
>> (Where do the symlinks point to? All the mapping is
>> stored in memory but symlinks point to file objects? This is little
>> confusing to me)
>> Can you please provide insight into this?
>
> The idea is to use symlinks to present a single namespace to clients
> that is backed by multiple file systems (hdfs or other supported
> hadoop file systems). Eg a "root" HDFS file system could contain links
> to other file systems, eg /dir1 could point to S3, /dir2 could point
> to a local file system, /dir3 could point to another HDFS file system,
> etc. Clients always contact the "root" HDFS file system but are
> transparently redirected to other file systems by symlinks. This way a
> single namespace is partitioned across multiple file systems, but the
> client only needs to know about the root file system. This
> partitioning is static (you have to establish the symlinks), though
> you can grow on the fly by adding file systems and links that point to
> them.
>
> Thanks,
> Eli
>

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