[olug] Combining SDD and HDD drives?

[Kevin D. Snodgrass]

--- On Sat, 7/10/10, Dan Linder <dan at linder.org> wrote:
> My current laptop has a 320GB 5400RPM
> drive.  Space isn't an issue as much
> as speed.   I've had 7200 RPM drives in the
> past and while they are faster,
> I can't justify the purchase of a new drive for a ~5-10%
> speed-up in my
> work.
> 
> What I'd love is the 25-35% speed-up a SSD would provide
> but a 320GB HDD
> (even a 256GB) is out of my price range.  That got me
> to thinking...
> 
> My "working set" of these files are fairly small ~80GB, but
> I can't split
> the files across different filesystems for other reasons.
> 
> If I could find a filesystem or multi-disk (MD) driver that
> would allow for
> multiple physical drives to be put into a pool, and then
> the most used
> sectors would be stored on the SSD while the rest would be
> left on the HDD.
> 
> I think this is a "hierarchial filesystem" idea, but I
> can't find any notes
> on how this might be setup for my situation.
> 
> Any ideas?

In comp.os.linux.setup, on July 5, 2010, "Arno" asked almost the exact question with Subj: RAID1: Read-prefer one disk?

Looks like man mdadmin, and search for "--write-mostly", might be your answer...

Arno posts results later under Subj: RAID1: HDD+SDD -- some benchmarks

Kevin D. Snodgrass