[dm-devel] [RFC] [DONOTAPPLY] [PATCH] enhanceio: STEC EnhanceIO SSD caching software for Linux kernel

[Kent Overstreet]

On Fri, Feb 1, 2013 at 4:57 PM, Michel Lespinasse <walken at google.com> wrote:
> On Fri, Feb 1, 2013 at 4:44 PM, Darrick J. Wong <darrick.wong at oracle.com> wrote:
>> This is a patch to migrate STEC's enhanceio driver out of their github
>> repository and into the staging tree.  From their README:
>>
>> "EnhanceIO driver is based on EnhanceIO SSD caching software product developed
>> by STEC Inc. EnhanceIO was derived from Facebook's open source Flashcache
>> project. EnhanceIO uses SSDs as cache devices for traditional rotating hard
>> disk drives (referred to as source volumes throughout this document).
>> EnhanceIO can work with any block device, be it an entire physical disk, an
>> individual disk partition,  a RAIDed DAS device, a SAN volume, a device mapper
>> volume or a software RAID (md) device."
>
> What's your take on the benefits of this vs bcache ?

I've been trying to review it it for cache coherency and consistency
wrt. power failures, but the complete lack of high level documentation
is making that difficult.

I saw some benchmarks the other day where on writes EIO was faster
than the raw device, which was... suspicious.