flashblock

flashblock
==========

A simple simulated flash-based block device. The idea is to simulate the
behaviour of a (NAND) flash-based storage device, which only allows write-once
sectors and erasing of whole erase blocks. A simple Flash Translation Layer
(FTL) has been implemented to expose block device sematics.

The reason for writing this is mainly a learning exercise and curiosity. I
wanted a tool to be able to measure the effect of write amplification and erase
block lifetimes, on certain Linux workloads (git, compiling, databases, etc).
Although SSDs generally expose some metrics through SMART, finer granularity
statistics such as histograms of erase block utilisation or erase counts are
not visible to the average user.

So to gather these kind of statistics, I decided to implement a block device
which simulates (very poorly) an SSD and tracks these statistics.

This is a work-in-progress, so only basic histograms and logs are outputted.
Machine-readable/analysable logs are a future me problem. In addition, the
basic FTL isn't very good, and doesn't accurately simulate the behaviour of
NAND flash. In particular, it performs word-sized writes, which flash devices
may not do (at least from what I've seen looking at a few datasheets).

License
=======

flashblock is released under the MIT license.