* How well does bcache cope with frequently changing cache device?
@ 2016-09-04 17:08 Clemens Eisserer
2016-09-06 2:27 ` Kent Overstreet
0 siblings, 1 reply; 2+ messages in thread
From: Clemens Eisserer @ 2016-09-04 17:08 UTC (permalink / raw
To: linux-bcache
Hi,
I am thinking about working with a root-fs on an external disk which
can be shared amongst different computers.
For this use-case the internal SSD could be used as caching device,
speeding up the access to the relativly slow external storage.
What I wonder is how well bcache can cope with changing caching
devices? Great would be if bcache could detect when a backing decive
was used with a different caching device in the meantime and
automatically invalidate the old/stale caching device - but to keep
the cache unmodified when this was not the case.
Is this use-case possible with bcache?
Thank you in advance, Clemens
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: How well does bcache cope with frequently changing cache device?
2016-09-04 17:08 How well does bcache cope with frequently changing cache device? Clemens Eisserer
@ 2016-09-06 2:27 ` Kent Overstreet
0 siblings, 0 replies; 2+ messages in thread
From: Kent Overstreet @ 2016-09-06 2:27 UTC (permalink / raw
To: Clemens Eisserer; +Cc: linux-bcache
On Sun, Sep 04, 2016 at 07:08:04PM +0200, Clemens Eisserer wrote:
> Hi,
>
> I am thinking about working with a root-fs on an external disk which
> can be shared amongst different computers.
> For this use-case the internal SSD could be used as caching device,
> speeding up the access to the relativly slow external storage.
>
> What I wonder is how well bcache can cope with changing caching
> devices? Great would be if bcache could detect when a backing decive
> was used with a different caching device in the meantime and
> automatically invalidate the old/stale caching device - but to keep
> the cache unmodified when this was not the case.
>
> Is this use-case possible with bcache?
On its own bcache won't automatically invalidate the cached data - once a
backing device is associated with a certain cache, that backing device won't
come online until either the cache device is registered, or you detach it.
So you'll have to write your own scripts to check - "hey, is this backing device
associated with this cache device? if not, detach backing device, reformat cache
device, then attach cache device and backing device".
^ permalink raw reply [flat|nested] 2+ messages in thread
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2016-09-04 17:08 How well does bcache cope with frequently changing cache device? Clemens Eisserer
2016-09-06 2:27 ` Kent Overstreet
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