Bcache Testing: Large Files and a Wrap-Up

“This month we have been testing a new kernel patch named bcache
that takes SSDs and uses them as a cache for block devices (with
the typical device being hard drives). This article wraps up the
testing with an investigation of the throughput of large files and
summarizes all the testing to date (and there’s a lot of that).

“Introduction

“This is the fourth article in the testing series of a new
kernel patch called bcache. The really cool thing about bcache
— and the reason I’ve spent so much time on it — is
that it takes one block device and allows it to be a cache for a
second block device. What makes this special is that it is intended
to take SSD’s and make them cache devices for hard drives or RAID
arrays. Conceptually you could take a few inexpensive SSD devices
that cost around $100-$150 each, create a RAID-0 array, and use it
to cache a RAID-6 or even a RAID-5 array. I have waited for a long
time for the ability to cache hard drives using something like an
SSD or even a ramdisk to really improve storage performance when
performance is the most critical item (and, honestly, who doesn’t
like performance?).”

Complete
Story