David Rhodes Clymer | 12 Apr 00:47 2012

Resizing bcache backing store

In the case where the bcache backing store is resizeable (eg. a
logical volume), is it possible to resize the backing store without
breaking bcache? Let's say, for example, that I would
unmount/unregister /dev/bcacheX, resize the backing store,
reregister/remount the cache.

I imagine a better approach would be to layer LVM on the cache device
itself. However, in this particular case, I set up the bcache before I
had learned how to get LVM to use a bcache device as a PV.

-davidc
Kent Overstreet | 12 Apr 01:55 2012
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Re: Resizing bcache backing store

For the backing device, I think things will just work - you'll just
have to close and reopen the backing device in order for bcache to
notice the new size. Bcache's superblock doesn't remember the size, it
just goes off of what the size of the backing device is when it's
registered.

There's currently no way to make bcache notice the backing device has
grown to do it at runtime, though that ought to be fairly simple too.

On Wed, Apr 11, 2012 at 6:47 PM, David Rhodes Clymer
<david@...> wrote:
> In the case where the bcache backing store is resizeable (eg. a
> logical volume), is it possible to resize the backing store without
> breaking bcache? Let's say, for example, that I would
> unmount/unregister /dev/bcacheX, resize the backing store,
> reregister/remount the cache.
>
> I imagine a better approach would be to layer LVM on the cache device
> itself. However, in this particular case, I set up the bcache before I
> had learned how to get LVM to use a bcache device as a PV.
>
> -davidc
> --
> To unsubscribe from this list: send the line "unsubscribe linux-bcache" in
> the body of a message to majordomo@...
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
James Sefton | 1 Nov 20:06 2012
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Re: Resizing bcache backing store

Kent Overstreet <koverstreet <at> ...> writes:

> 
> For the backing device, I think things will just work - you'll just
> have to close and reopen the backing device in order for bcache to
> notice the new size. Bcache's superblock doesn't remember the size, it
> just goes off of what the size of the backing device is when it's
> registered.
> 
> There's currently no way to make bcache notice the backing device has
> grown to do it at runtime, though that ought to be fairly simple too.
> 
> On Wed, Apr 11, 2012 at 6:47 PM, David Rhodes Clymer
> <david <at> ...> wrote:
> > In the case where the bcache backing store is resizeable (eg. a
> > logical volume), is it possible to resize the backing store without
> > breaking bcache? Let's say, for example, that I would
> > unmount/unregister /dev/bcacheX, resize the backing store,
> > reregister/remount the cache.
> >
> > I imagine a better approach would be to layer LVM on the cache device
> > itself. However, in this particular case, I set up the bcache before I
> > had learned how to get LVM to use a bcache device as a PV.
> >
> > -davidc
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-bcache" in
> > the body of a message to majordomo <at> ...
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
(Continue reading)

Kent Overstreet | 2 Nov 16:20 2012
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Re: Resizing bcache backing store

On Thu, Nov 01, 2012 at 07:06:01PM +0000, James Sefton wrote:
> Kent Overstreet <koverstreet <at> ...> writes:
> 
> > 
> > For the backing device, I think things will just work - you'll just
> > have to close and reopen the backing device in order for bcache to
> > notice the new size. Bcache's superblock doesn't remember the size, it
> > just goes off of what the size of the backing device is when it's
> > registered.
> > 
> > There's currently no way to make bcache notice the backing device has
> > grown to do it at runtime, though that ought to be fairly simple too.
> > 
> > On Wed, Apr 11, 2012 at 6:47 PM, David Rhodes Clymer
> > <david <at> ...> wrote:
> > > In the case where the bcache backing store is resizeable (eg. a
> > > logical volume), is it possible to resize the backing store without
> > > breaking bcache? Let's say, for example, that I would
> > > unmount/unregister /dev/bcacheX, resize the backing store,
> > > reregister/remount the cache.
> > >
> > > I imagine a better approach would be to layer LVM on the cache device
> > > itself. However, in this particular case, I set up the bcache before I
> > > had learned how to get LVM to use a bcache device as a PV.
> > >
> > > -davidc
> > > --
> > > To unsubscribe from this list: send the line "unsubscribe linux-bcache" in
> > > the body of a message to majordomo <at> ...
> > > More majordomo info at  http://vger.kernel.org/majordomo-info.html
(Continue reading)


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