Re: support for physical ramdisk

On Wed, Jan 19, 2011 at 5:14 PM, Cory Coager [off-list ref] wrote:

I would think even a low end DDR2 module would saturate the SATA interface
bandwidth.

How would external journal to bcache help?

Well, ram is more expensive per gigabyte than SSDs, particularly if
you've got something with a battery attached - the idea would be to
use your SSD for buffering 80 gb or so of writes, but then buffer all
of bcache's metadata writes in battery backed-up ram, significantly
decreasing the number of write IOPS to the SSD, and making it so
pretty much all the writes to the SSD are big contiguous writes.

On 01/19/2011 08:03 PM, Kent Overstreet wrote:

quoted

Ahh, that makes sense. I'd be curious what performance you get - it
certainly wasn't designed with ram in mind. You'll want to play around
with the bucket size and see what works best, too.

Also, in the future I'm going to add support for an external journal
to bcache - that could be the best of both worlds, for you.

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