An Oracle blog about ZFS Storage

  • October 9, 2015

New Readzilla features (L2ARC)

Steve Tunstall
Principle Storage Engineer

 The ZFSSA keeps evolving, and one of the best new code features are the improvements made in the L2ARC. This is the area controlled by the optional "Readzilla" SSDs that we sell with most systems. Basically, they are and extension of the DRAM. You can refresh yourself with ARC from my earlier posting. As a quick reminder, DRAM is your ARC (adaptive responsive cache), and Readzillas are your L2ARC (level 2). Being SSDs, they are 1000 times slower than ARC, but 1000 times faster than spinning disk. So a nice middle-ground for holding extra cache that your DRAM no longer needs to hold, but still fast to read when requested. The improvements in the latest code are:

  • reduce its own memory footprint,
  • be able to survive reboots,
  • be managed using a better eviction policy,
  • be compressed on SSD,
  • and finally allow feeding at much greater rates then ever achieved before.
  • To read more about these features, once again, I am pointing you to Roch's great blog, so I don't have to re-invent the wheel here.


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