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From AJ>
Subject Re: Anyone using Facebook's flashcache?
Date Mon, 18 Jul 2011 17:53:07 GMT
On 7/18/2011 4:14 AM, H├ęctor Izquierdo Seliva wrote:
>> Hector, some before/after numbers would be great if you can find them.
>> Thanks!
> I'll try and get some for you :)
>> What happens when your cache gets trashed?  Do compactions and flushes
>> go slower?
> If you use flashcache-wt flushed and compacted sstables will go to the
> cache.
> All reads are cached, so if you compact three sstables into one, you are
> stuffing your cache with a lot of useless crap and evicting valid blocks
> (flashcache won't honor any of the hints set with fadvise, as it's a
> block cache layer and doesn't know of them anyway). If your write rate
> is low it might work for you.

Interesting.  So, there is no segregation between read and write cache 
space?  A compaction or flush can evict blocks in the read cache if it 
needs the space for write buffering?

>> aj

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