"SSDs" entries

The truth about MapReduce performance on SSDs

Cost-per-performance is approaching parity with HDDs.

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Karthik Kambatla co-authored this post.

It is well-known that solid-state drives (SSDs) are fast and expensive. But exactly how much faster — and more expensive — are they than the hard disk drives (HDDs) they’re supposed to replace? And does anything change for big data?

I work on the performance engineering team at Cloudera, a data management vendor. It is my job to understand performance implications across customers and across evolving technology trends. The convergence of SSDs and big data does have the potential to broadly impact future data center architectures. When one of our hardware partners loaned us a number of SSDs with the mandate to “find something interesting,” we jumped on the opportunity. This post shares our findings.

As a starting point, we decided to focus on MapReduce. We chose MapReduce because it enjoys wide deployment across many industry verticals — even as other big data frameworks such as SQL-on-Hadoop, free text search, machine learning, and NoSQL gain prominence.

We considered two scenarios: first, when setting up a new cluster, we explored whether SSDs or HDDs, of equal aggregate bandwidth, are superior; second, we explored how cluster operators should configure SSDs, when upgrading an HDDs-only cluster. Read more…

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How Flash changes the design of database storage engines

High-performing memory throws many traditional decisions overboard

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Over the past decade, SSD drives (popularly known as Flash) have radically changed computing at both the consumer level — where USB sticks have effectively replaced CDs for transporting files — and the server level, where it offers a price/performance ratio radically different from both RAM and disk drives. But databases have just started to catch up during the past few years. Most still depend on internal data structures and storage management fine-tuned for spinning disks.

Citing price and performance, one author advised a wide range of database vendors to move to Flash. Certainly, a database administrator can speed up old databases just by swapping out disk drives and inserting Flash, but doing so captures just a sliver of the potential performance improvement promised by Flash. For this article, I asked several database experts — including representatives of Aerospike, Cassandra, FoundationDB, RethinkDB, and Tokutek — how Flash changes the design of storage engines for databases. The various ways these companies have responded to its promise in their database designs are instructive to readers designing applications and looking for the best storage solutions.

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