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From Nick Dimiduk <ndimi...@apache.org>
Subject Re: hbase.bucketcache.percentage.in.combinedcache with ioengine=<FILE ON SSD> on HBase 0.98
Date Tue, 06 Oct 2015 20:03:06 GMT
Configuring offheap cache in 0.98 is a huge PITA. There are some example
configs [0] linked from my old blog post [1], maybe that's a starting
point? I also worked with our docs team to get this explained [2] in a
somewhat useful way, using an algorithm/formula as the basis of the
explanation. That algorithm was eventually implemented into Ambari's Stack
Advisor script [3], so if you're really feeling brave you can try to
extract it from there.

But really, you should upgrade to 1.x and enjoy Stack's nice work on making
it simpler to configure.

Good luck,
-n

[0]: https://github.com/ndimiduk/perf_blockcache
[1]: http://www.n10k.com/blog/blockcache-showdown/
[2]:
http://docs.hortonworks.com/HDPDocuments/HDP2/HDP-2.3.0/bk_Sys_Admin_Guides/content/ref-db219cd6-c586-49c1-bc56-c9c1c5475276.1.html
[3]:
https://github.com/apache/ambari/blob/trunk/ambari-server/src/main/resources/stacks/HDP/2.2/services/stack_advisor.py#L552-L579

On Tue, Oct 6, 2015 at 11:36 AM, Anthony Nguyen <anthony.an.nguyen@gmail.com
> wrote:

> Hi all,
>
> I'm running HBase 0.98, with the complicated percentage.in.combinedcache
> setting. What's the best way to set the percentage.in.combinedcache setting
> when using a file on SSD storage as the location for ioengine? The SSD
> drive is dedicated for the cache. I don't want to modify the LruBlockCache
> settings at all, keeping it available for index + bloom and just add the L2
> SSD cache for storage for the data blocks (not the raw L1+L2 method).
>
> My confusion is in how I should best modify the percentage.in.combinedcache
> setting. HBASE-11520 makes things much clearer, but unfortunately it isn't
> in 0.98. To me, it doesn't make much sense to have L1 be set to
> hbase.bucketcache.size (100G) * (1.0 -
> hbase.bucketcache.percentage.in.combinedcache (default=0.9) = 1G when I
> want the L1 to be the same as it was prior to bucketcache
> (hfile.block.cache.size * heap).
>
> Also, I don't want to have any direct addressing of memory since my offheap
> is completely on SSD. Does this mean I shouldn't change
> XX:MaxDirectMemorySize?
>
> Could someone sanity check these settings for me? Thanks!
>
> 30 GB RAM
> ~120 GB SSD
> HBASE_REGIONSERVER_OPTS -Xms17G -Xmx17G
> XX:MaxDirectMemorySize <- Don't touch since we're not using direct byte
> buffers, right?
>
> <property>
>   <name>hbase.bucketcache.ioengine</name>
>   <value>file:/mnt/foo/bar</value>
> </property>
> <property>
>   <name>hbase.bucketcache.percentage.in.combinedcache</name>
>   <value>0.9</value>
> </property>
>
> <property>
>   <name>hfile.block.cache.size</name>
>   <value>0.6</value>
> </property>
>
> <property>
>   <name>hbase.bucketcache.size</name>
>   <value>102400</value>
> </property>
>

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