Speakers
Speakers
Tuesday, 5/27/14 Adam Manzanares, Research Staff Member, HGST
Title: System Software Updates For Shingled Magnetic Recording
Abstract: Shingled Magnetic Recording (SMR) technologies aim to increase the areal density of hard disk drives (HDD's), This increase is achieved by narrowing data tracks of the HDD, which demands smaller magnetic poles on write heads to write data exclusively to a particular track. The poles can only be narrowed to a point, until the magnetic field generated by the poles is no longer strong enough to flip data bits on a track. To overcome this limitation, SMR drives write using a magnetic field hat overlaps many tracks. These overlapping tracks demand large contiguous writes to achieve reasonable performance, but also require changes to systems software. To limit the impact of shingling, SMR drives are broken into several zones, such that each zone can be written to without damaging any other zone. In this talk I will discuss the impact that the SMR properties have on systems software and our efforts in this area.
Background Information:
http://www.cs.cmu.edu/~./garth/papers/05_feldman_022-030_final.pdf
http://www.t10.org/cgi-bin/ac.pl?t=f&f=zbc-r01a.pdf [ Section 4 & 5 ]
Thursday, 4/24/14 Dick Sites, Senior Staff Engineer, Google
Title: Identifying Dark Latency
Abstract: In astronomy and cosmology, dark matter is hypothetical matter that is undetectable by its emitted radiation, but whose presence can be inferred from gravitational effects on visible matter. [Wikipedia]
By analogy, dark latency in software is latency that is undetectable directly, but whose presence can be inferred from overall application delays. We bring four tools to bear to observe dark latency in some Google web services, then identify and fix several root causes, in low-level Google libraries and in the TCP stack.