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From: Christian Stroetmann on 4 Aug 2010 14:50
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
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
Christian *<:o) O>-< -(D)>-<
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