DiskSim v4.0 includes bug fixes and three primary additions: the DIXtrac disk characterization tool [Schindler99], a MEMS-based storage device model [Griffin00, Schlosser03], and a new layout model generic enough for all logical-to-physical mappings that we have seen.
DiskSim is an efficient, accurate, highly-configurable disk system simulator originally developed at the University of Michigan and enhanced at CMU to support research into various aspects of storage subsystem architecture. It is written in C and requires no special system software (just basic POSIX interfaces). DiskSim includes modules for most secondary storage components of interest, including device drivers, buses, controllers, adapters, and disk drives. DiskSim also includes support for a number of externally-provided trace formats and internally-generated synthetic workloads, and includes hooks for inclusion in a larger scale system-level simulator. It has been used in a variety of published studies (and several unpublished studies) to understand modern storage subsystem performance [Ganger93a, Worthington94], to understand how storage performance relates to overall system performance [Ganger93, Ganger95, Ganger95a], and to evaluate new storage subsystem architectures [Worthington95a].
DiskSim has been validated both as part of a more comprehensive system-level model and as a standalone subsystem. In particular, the disk module (which is extremely detailed) has been carefully validated against 10 different disk models from 5 different manufacturers. The accuracy demonstrated exceeds that of any other disk simulator known to the authors (e.g., see Ruemmler and Wilkes' article in the March 1994 issue of IEEE Computer).
Parameters for some disks against which we have validated DiskSim are included with the source code release (see below). For 4 of these disks, the parameters were extracted by a set of semi-automated, on-line algorithms described in [Worthington95, Worthington96]. For another 5 disks, the parameters were extracted automatically by a disk characterization tool called DIXtrac. Additional DIXtrac-provided parameters are added periodically to our on-line database of disk parameters.
A fairly complete description of what DiskSim can do and how to use it can be found in the Reference Manual below.
NOTE: Microsoft Research has created an idealized SSD model for DiskSim 4.0 (used in the USENIX 2008 paper "Design Tradeoffs for SSD Performance")
and is sharing it under a limited non-commercial (click-through) license
from the Microsoft Research download site.
NOTE: Instead of contacting the authors directly to find out more, or comment on disksim, please send mail to
DiskSim has been made freely available in order to further storage system research (and computer system research that in some way includes the storage system). All we ask is that you let us know, if and when you can, that you are using and what kind of fabulous things you do with it.
Please send bug reports, experiences, and problems to
If you find disksim useful, please let us know about it!
There are two public mailing lists for DiskSim:
These mailing lists are moderated such that only subscribers can post; please subscribe before mailing the list.
A zipped archive file of past disksim email list posts is available.
We thank the members and companies of the PDL Consortium: Amazon, Google, Hitachi Ltd., Honda, Intel Corporation, IBM, Meta, Microsoft Research, Oracle Corporation, Pure Storage, Salesforce, Samsung Semiconductor Inc., Two Sigma, and Western Digital for their interest, insights, feedback, and support.