[Colloq] REMINDER: Sivan Toledo, Tel-Aviv Univ., TODAY, 12pm

[Rachel Kalweit]

College of Computer and Information Science Colloquium

Presents:
Sivan Toledo
Tel-Aviv University

Who will speak on:
Algorithms and Data Structures for Flash Memories

Wednesday, March 1, 2006
12:00pm
366 West Village H
Northeastern University

Abstract:

Flash memories are the most common form of solid-state nonvolatile
memory. Flash is everywhere: in digital cameras, portable music players,
mobile phones, handheld computers, desktops, laptops, servers, routers
and modems, and more; the list is almost endless.

Flash memories have some peculiar hardware characteristics. The most
important characteristic is an endurance limit: each physical memory
cell can be erased and rewritten a limited number of times. Another
important characteristic of some flash devices is large erase blocks:
data can only be written to erased memory cells, but an erasure erases
not one bit or one byte, but a large block of memory (say 64KB).
Although small data objects can be modified by copying the content of a
block to RAM, modifying the object in RAM, erasing the flash block and
writing the modified content to it, this read-modify-write method is
very inefficient.

The endurance limit and the other unique characteristics of flash
require specialized algorithms and data structures. Although
flash-specific techniques have been invented in the last 15 years or so,
not much basic research has been conducted on this topic. Over the last
two years my students and I have been investigating flash algorithms and
data structure. The talk will describe the essence of our results. In
particular, the talk will describe:

* an efficient file system for a type of flash memory called NOR flash;
the file system uses several novel data structures, some based on
persistent data structures

* support for atomicity and explicit transactions in the file system

* error detection and crash recovery in the file system

* a data structure for supporting a persistent object store (for Java)
on NOR flash, including support for garbage collection and for
transactions in RAM-limited systems

* competitive analysis of techniques designed to avoid early wear due to
the endurance limit (such techniques are usually called wear-leveling
techniques)

The talk is based on joint research with Eran Gal, Michal Spivak, Avi
Ben Aroya, and Yossi Azar.

Sivan Toledo is Associate Professor of Computer Science. He was educated
in Tel-Aviv University (BSc and MSc, both 1991) and at the Massachusetts
Institute of Technology (PhD, 1995). He worked as a postdoctoral
researcher at the IBM TJ Watson Research Center in New York and at the
Xerox Palo-Alto Research Center in California prior to joining Tel-Aviv
University in 1998.

Host: Ravi Sundaram

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