Hola Everybody;
On the 04.08.2010 19:40, Mingming Cao wrote:
On Thu, 2010-07-29 at 22:17 +1000, Dave Chinner wrote:
On Wed, Jul 28, 2010 at 03:00:48PM -0700, Mingming Cao wrote:
On Wed, 2010-07-28 at 01:38 +0200, Christian Stroetmann wrote:
At the 28.07.2010 00:00, Ben Chociej wrote:
Wouldn't this feature be useful for other file systems as well, so that
a more general and not an only Btrfs related solution is preferable?
Would certainly nice to add this feature to all filesystem, but right
now btrfs is the only fs which have multiple device support in itself.
Why does it even need multiple devices in the filesystem? All the
filesystem needs to know is the relative speed of regions of it's
block address space and to be provided allocation hints. everything
else is just movement of data. You could keep the speed information
in the device mapper table and add an interface for filesystems to
query it, and then you've got infrastructure that all filesystems
could hook into.
The tracking features dont' appear to have anything btrfs specific
in them, so t iseems wrong to implement it there just because you're
only looking at btrfs' method of tracking multiple block devices
and moving blocks....
I agree hot data tracking could be done at vfs layer. The current hot
data temperature calculation and indexing code is very self-contained,
and could be reuse to other fs or move up to vfs. We could define a
common interface to export to hot data tempreture out. The relocation
eventually has to be filesystem specific. btrfs does cow and knows where
is the data on/off SSD directly makes the relocation to and from very
straightforward.
Thanks for your thumb up. But maybe other interested persons should also
point their thumbs up at first before investing the effort of its
implementation. I mentioned this feature, because it is a trend that got
momentum in the area of (storage) virtualization and in this way in the
fields of cloud computing and service computing as well.
And: My both thumbs are already up. :D
Mingming
Christian *<:o) O>-< -(D)>-<
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