Surprises in disk reliability from Microsoft’s “free cooled” datacenters

HH5At Usenix ATC’16 last week, there was a “best of the rest” session which repeated selected papers presented at FAST’16 earlier this year. One that caught my interest was discussing disk reliability in free cooled data centers at Microsoft (Environmental conditions and disk reliability in free-cooled datacenters, see pp. 53-66).

The paper discusses disk reliability at 9 different datacenters in Microsoft for over 1M drives over the course of 1.5 to 4 years vs. how datacenters were cooled.
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Testing filesystems for CPU core scalability

IMG_6536I attended HotStorage’16 and Usenix ATC’16 conferences this past week and there was a paper presented at ATC titled “Understanding Manicure Scalability of File Systems” (see p. 71 in PDF) by Changwoo Min and others at Georgia Institute of Technology. This team of researchers set out to understand the bottlenecks in a typical file systems as they scaled from 1 to 80 (or more) CPU cores on the same server.

FxMark, a new scalability benchmark

They created a new benchmark to probe CPU core scalability they called FxMark (source code available at FxMark), consisting of 19 “micro benchmarks” stressing specific scalability scenarios and three application level benchmarks, representing popular file system activities.

The application benchmarks in FxMark included: standard mail server (Exim), a NoSQL DB (RocksDB) and a standard user file server (DBENCH).

In the micro benchmarks, they stressed 7 different components of files systems: 1) path name resolution; 2) page cache for buffered IO; 3) node management; 4) disk block management; 5) file offset to disk block mapping; 6) directory management; and 7) consistency guarantee mechanism.
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