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https://issues.apache.org/jira/browse/HBASE-4056?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13061786#comment-13061786
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Jonathan Gray commented on HBASE-4056:
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Thanks for opening this JIRA.
What do you see as the primary benefit of using flash for the WAL? I've seen
some improvement in sequential write throughput, but not drastically different.
It seems to me that a significant benefit of using flash is the fast random
read access, and there are no random reads on the WAL.
One idea that has floated around is to do something like cache-on-write to copy
recently written files onto flash (in addition to HDFS) to allow for fast
random read access. Or use flash as some kind of extension to the block cache.
But regardless, making all of this stuff configurable and supporting more
diverse setups is a good thing in general. Some experiments and benchmarks
around this would be awesome. Good stuff.
> Support for using faster storage for write-ahead log
> ----------------------------------------------------
>
> Key: HBASE-4056
> URL: https://issues.apache.org/jira/browse/HBASE-4056
> Project: HBase
> Issue Type: New Feature
> Reporter: Praveen Kumar
> Priority: Minor
> Labels: features
>
> On clusters with heterogeneous storage components like hard drives and flash
> memory, it could be beneficial to use flash memory for write-ahead log. This
> can be accomplished by using client side mount table support (HADOOP-7257)
> that is offered by HDFS federation (HDFS-1052) feature. One can define two
> HDFS namespaces (faster and slower), and configure HBase to use faster
> storage namespace for storing WAL.
> This is an abstract task that captures the idea. More brainstorming and
> subtasks identification to follow.
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