I wonder how much Heinz's replicator code could work with this...
Heinz et al have a "remote replicator" target that 'logs' requests to
a local device and then pushes them to remote devices. I could
imagine the log device being the fast device, and the remote devices
being the slow devices.
So, I'm not sure how much overlap there is here, but it's something to
think about.
brassow
On Jan 14, 2009, at 1:43 PM, Ty! Boyack wrote:
Hi all,
I'm seeing a good bit of interest in multi-tier storage in high end
systems, and was wondering if this functionality could be offered by
device-mapper.
By multi-tier, I'm speaking of systems where various speed/quality
storage units are used in an analogous way to the way cache is used
for memory: The most recently/often used data blocks are placed on
the fastest storage device, then over time gets flushed out to
slower systems. It seems the trend is to use a smaller array of 15k
rpm SAS drives as the first tier, then flush it out to much larger
arrays of 7200 rpm SATA drives as the second tier.
While this clearly has benefits in large systems, I would think the
same concept could be brought in-box as well, by using a fast 15k or
solid state drive as the first tier, and then pushing out to 7200
rpm SATA as a second tier.
My interest is more in the large system side, but if this
functionality was available and easy to use, I could see it getting
wide adoption in smaller systems too -- just as RAID was once
limited to big systems, this could be a cool technology to make
available to all.
So the questions:
1) Is device-mapper the right layer to look at applying this?
2) If so, any ideas on how hard it would be to implement?
3) If device-mapper is not the right place, any idea where this
functionality should go, or if it is already out there in another
form?
Thanks -- I would love to hear any thoughts or questions on this.
-Ty!
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Ty! Boyack
NREL Unix Network Manager
ty@xxxxxxxxxxxxxxxxxx
(970) 491-1186
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